2006-2010 Hyundai Sonata Blowing Hot on One Side, Cold on the Other: Blend Door Actuator Fix (Dorman 604-310 / 604-308)

If your 2006 to 2010 Hyundai Sonata blows hot air out of one side of the dash and cold air out of the other, and the mode buttons still send air to the floor, face, and windshield like they should, the problem is almost always the temperature (blend door) actuator on the side that stopped behaving. It is not the heater core. On the NF Sonata the passenger-side actuator hides behind the glove box and the driver-side one sits under the dash above the driver footwell. Swap the dead one (owners used Dorman 604-310 for the passenger side and 604-308 for the driver side), make sure the little guide plate on the new motor matches the old one, line the pin up in its track, and both sides start following the knob again.

I am Jay, and this is one of my favorite kinds of repair: a symptom that sounds scary and expensive, a part that costs less than a tank of gas on a good day, and a job you can do in the driveway with a couple of short screwdrivers and a lot of patience. The owners on hyundai-forums.com worked this out more than a decade ago. One of them did it at 65 years old, flat on his back under the dash, and then wrote up every step so the rest of us would not have to guess. This article walks through what they found, how to confirm it on your own car, the removal and install they actually did, and the handful of cases where a new actuator did not fix it.

What this problem looks like on an NF Sonata

The NF Sonata (2006 to 2010 in North America) with dual climate control has a separate temperature door for each side of the HVAC box, and each door has its own small electric motor. When one of those motors quits, that side of the car freezes at whatever temperature the door was sitting at when it died. The other side keeps working normally. That is why the symptom is so lopsided.

Here is how the owners in the two source threads described it:

• Forum member Hwy61, on a 2009 Sonata at about 84,000 miles, was on a Thanksgiving trip with 22F outside when lukewarm air came out of the driver side only, no matter the setting. The passenger side blew air that was, in his words, “22F cold.”
• TimH3502, on a 2008 Limited, had the opposite: the passenger side would only blow hot air.
• Another owner had the A/C stop cooling on the driver side only, while heat and fan worked on both sides.
• In every case the floor, dash, and windshield vents still switched normally. Only the temperature on one side was stuck.

That last point matters. If the mode vents still move, the mode actuator is fine, and you are looking at a temperature actuator. Tim made the distinction in his write-up: the part you want is the one that controls the temperature of the air, “not to be confused with the motor/actuator that controls what vents air flow comes out of.”

Stuck hot or stuck cold depends on where the door died

Do not let the direction throw you. A dead actuator can leave its side stuck hot or stuck cold. It just depends on where the door was parked when the motor gave up. Hwy61’s passenger side died cold in winter. Tim’s passenger side died hot in July. Same part, same failure.

Rule out the easy stuff first

Before he ever pulled the glove box, Hwy61 went through the checks that most people on the forum recommend. These take a few minutes and they keep you from tearing into the dash for nothing.

Coolant level and temperature gauge

Check that the coolant is full and that the temperature gauge reads where it always has. Hwy61 noted his needle ran just below the middle mark, as it always had. If you are low on coolant or the engine never warms up, both sides will be weak, not just one.

Fuses

Check the fuses. He pointed out there is a fuse box under the hood on the driver side and another to the left of the steering column, behind a plastic door you pull off by its finger hold. He warned that those inside fuses sit recessed about 10 inches back and the door is small, so bring a light.

Feel the heater hoses

With the engine warm, feel the two hoses behind the engine that run through the firewall. On his car they were both hot. If both are hot and only one side of the dash is cold, coolant is getting to the heater core. A heater core cannot heat just one side of the car, so a one-sided problem with hot hoses points straight at the door and its actuator.

Confirm the actuator is dead

The threads give you three good ways to confirm the actuator before you spend money.

The finger test

Hwy61 added this one after the fact. With the engine warm, you can reach a finger up onto the actuator and feel whether it moves while someone runs the temperature up and down. If it does not move, the part is bad. His original would not move at all.

Pull it and move the door by hand

Forum member Nismo06 described the definitive check. Once the actuator is off, you can move the blend door yourself by moving the metal rod on the mechanism. Push it to one extreme and you should get cold air. Push it to the other and you should get warm air. If you can change the air temperature that way, the actuator is the most likely culprit.

Tim added a detail for the passenger side. When he unscrewed the motor and slowly pulled it away, he could see and hear the door flap shut on its own once it was no longer being held, and then the air on that side changed temperature. On the driver side, if gravity does not flap the door shut, he said you should see a metal (silver) actuator arm you can move by hand with the motor removed.

Test it hanging on the harness

Hwy61 also recommended that once the old actuator is out, you plug it back into its wiring, let it hang, and run the temperature control up and down one more time to confirm it really does not turn. Then plug in the new one and confirm it does turn before you bolt anything in. If the new one does not move either, he said, go back and make sure you did not miss a bad fuse.

Which side, and which part

This is where most people get tripped up, so take it slow.

Passenger side versus driver side

Hwy61 was surprised to learn there are two of these. Forum member sbr711 explained it: the actuator with the blue arm is typically the driver side, and the one with the white arm is the passenger side. He also pointed out that the driver side unit is easy to see with a light under the dash, “kinda out in the open.” Another owner who suspected his driver side was the bad one called it lucky, since you can just reach up there with a screwdriver.

Hwy61 guessed the easy-to-reach driver side is the reason his passenger side was the one that went bad. Whether or not that is why, plan on the passenger side being the harder job.

Part numbers owners used

Bill2008Ltd, who did the passenger side on a closely related 2008 Azera, posted the Dorman numbers:

• Driver side actuator: Dorman 604-308 (blue plastic lever)
• Passenger side actuator: Dorman 604-310 (white plastic lever)

Tim ordered his as a Dorman 604-308 from Amazon, and what showed up looked to him like it was made by Woory, which he said is the OEM supplier in Korea.

One owner in the first thread listed the Hyundai catalog numbers he found for a 2009 Sonata Limited with auto climate control, including temp door 97159-3K000, mode 97154-3K000, inlet door 97124-3K600, and assembly 97160-3K000. He was asking for confirmation, not giving it, so treat those as a starting point. sbr711’s standing advice in that thread is the right one: call or visit a Hyundai parts counter with your VIN so they can pull the correct number for your chassis. He also warned a 2011 owner that the 2011 Sonata is the YF chassis, not the NF, and likely takes a different part.

What it cost the owners

Hwy61 paid about $82 at NAPA. Tim paid $46 and figured a dealer or shop would want $250 to $300. Bill paid about $50 for the Dorman. Another owner, mdgarnett, got shop quotes of $350 to $450 and did it for less than $40 in parts. Prices will be different today, but the gap between parts and labor is still the whole reason to do this yourself.

The guide plate gotcha

This is the single most useful tip in either thread, and both write-ups ran into it independently.

The actuator has a small plastic cam or guide plate on the back (Tim said it “kinda looks like human ear”). That guide plate has a track, and the pin on the blend door linkage rides in that track. When Hwy61 compared his new part to his old one, the new blue guide plate was reversed from the old one, even though NAPA had checked the crossover numbers. Tim got the same thing: his new part had a guide plate that looked like a mirror image of the old one, as if it were meant for the other side.

The fix both of them used was simple. The guide plates snap off. Hwy61 snapped his old yellow one onto the new actuator and it worked fine. He noted they will only snap on in one position. Tim popped off his old plate and snapped it onto the new motor too. RubbernGlue swapped the blue and yellow on a NAPA part and was done.

Two owners asked how hard it is to get the plate off without breaking anything. littlelegs, working on a right-hand-drive 2008 Santa Fe, worried his seemed stuck with yellowish glue. A day later he reported back that the new cam pried off and the old one slipped on perfectly, and he had heat and A/C on both sides again.

So before you start screwing in the new actuator, hold the old one and the new one side by side and compare the guide plates. If they do not match, swap the old one onto the new motor.

Passenger side replacement, step by step

Hwy61’s write-up spells out the passenger-side job clearly, and Tim’s pictures follow the same path, so here is that procedure in order. I have only included steps the two threads actually describe. His original photos were hosted on Photobucket and no longer display (another owner asked him to re-post them in 2018), so read each step with the car in front of you.

Tools the owners used

Hwy61 said you do not need many tools: a 10mm socket for the battery, small screwdrivers, and a small ratchet, and much of the work is done by feel. Later owners added:

• A short stubby #2 Phillips for the lower right screw (sonata08ltd)
• A #2 Phillips about 3 inches long with a slim handle for the left screw (sonata08ltd)
• A Phillips ratchet for the top right screw (sonata08ltd)
• A Phillips drill bit turned with pliers for the upper screw (Tim)
• A short screwdriver for the upper screw; nacho used a Victorinox
• A rag to stuff in the opening below the actuator so screws do not disappear
• A light, because you will be looking up into a dark hole

Step 1: Disconnect the battery

Use the 10mm socket and disconnect the negative terminal. Hwy61 said you will want to reconnect it a couple of times along the way to test parts. You will also need to reset the clock at the end.

Step 2: Empty and drop the glove box

Empty the glove box. On each side there is a rubber stop. Pull the front edge of each one out a little and push it inward toward the center of the box. They like to jump back into place, so just pull them out again until the box can come forward. The strut on the right side will stop it partway.

Step 3: Release the strut

Pull the lower end of the strut arm off its pin. It slips off easily. Now the box can drop all the way down. Hwy61 pointed out this is the same way you get to the cabin filter door, and that the filter should be changed about every year. mdgarnett replaced his while the glove box was out.

Step 4: Remove the glove box

Two black plastic pins hold the glove box to the frame. Support the box and slide the pins all the way out, and the box comes free. Set it somewhere safe and put the pins somewhere you will find them again. Hwy61 suggested a cup holder.

Step 5: Remove the kick plate cover

The kick plate cover is held by two screws. At the firewall end it has a tongue that sits in a steel slot, so it lifts out once the screws are out. Remember that tongue for reassembly.

Step 6: Loosen the floor duct

You do not need to remove the blower motor or disconnect any of the wires you see. There is one Phillips screw holding the end of the floor duct. Remove it. Hwy61 could not remove that piece of duct, but he could wiggle it around, and you will need to.

Step 7: Stuff a rag under the actuator

Before you start on the actuator screws, sonata08ltd’s tip: stuff a rag into the opening below the actuator so tools and screws do not fall in. Do not forget to pull it out at the end.

Step 8: Unplug the harness

Press down on the white button to release the wiring connector. Hwy61 was firm about this: do not pull on the wires. They are small.

Step 9: Remove the three outer screws, and only those

The actuator has six screws. Tim explained it: three outer screws hold the motor frame to the HVAC box, and three inner screws hold the motor to its own frame. Only remove the three outer ones. Hwy61 said the same thing and added that one screw is hidden behind the floor duct, so you will need to wiggle the duct and angle in on that rearward screw. He called the space “about large enough for one hand and a small screw driver.”

Do not try to remove the steel control rod coming from the device. It stays where it is on both ends.

Step 10: Test the old one, then test the new one

With the old actuator out, plug it back in, let it hang, reconnect the battery, and run the temperature up and down to confirm it does not turn. Then compare the guide plates and swap if needed, plug in the new one, and confirm it turns. Hwy61 said that rotation is “what you want to see.”

Step 11: Match the door and actuator positions

The owners who had trouble with alignment all landed on the same idea: get the new actuator and the door at the same end of their travel before you bolt it in. They did it slightly differently.

• sonata08ltd reached in and moved the blend door by hand to the vertical (HEAT) position. With the new actuator plugged in, he let the engine run 10 to 15 minutes to warm up, set the control to HEAT at maximum so the actuator drove to its heat position, shut the car off, disconnected the negative battery cable, and installed it.
• Nismo06 did the same thing with max heat: let the actuator move, unplug it, move the car’s metal rod to the extreme heat position, then install.
• santa22 went the other way. He set the A/C to the coldest setting so the lever moved to an easy install position, with the rod on the car side in the down position.

Pick one end and stay consistent. The point is that the actuator and the door agree on where “full” is.

Step 12: Install the new actuator

Fit the new actuator so the pin sits in the track on the guide plate and the three screw holes line up. Tim said lining the guide plate up with the pin can take a couple of tries. Hwy61 said getting that hidden rear screw back in is even trickier than getting it out: “keep trying, you can get it.” Snap the wiring harness back on.

Step 13: Test before you close it up

Tim’s last check before putting the trim back: reconnect the battery, fire it up, and dial the temperature all the way up and all the way down while you watch the new motor open and close the door.

Step 14: Reassemble

Fit the kick plate tongue back into its slot and install its two screws. Position the glove box, push in the two black pins, reconnect the strut, and slide the box forward until the rubber stops pop back in flush. Fill the glove box, reconnect the battery if it is still off, and reset the clock.

How long it took

mdgarnett said his took about two and a half hours and thought he could do it in under an hour the second time. Ace805, on a 2008 Elantra that he said was nearly identical to Tim’s pictures, did it in about 30 minutes.

Getting more room behind the glove box

The passenger-side access is tight, and several owners found ways to open it up. Tim’s version removes the glove box and its frame, the lower panel under the dash, and the piece of duct, and he said that left fairly good access. Others added:

• RubbernGlue removed the dash trim. He snapped out the side panel of the dash, removed the silver bolts, took out the Phillips screw holding the faux wood trim, carefully snapped the trim out, and removed the bolts under it. That let him remove the lower duct.
• mdgarnett split the floor duct in half along its fasteners for more room. He said it was still a challenge.
• jim4802, doing the same job on a 2008 Veracruz, removed four more glove box screws and two bolts to get the floor duct out of the way.
• Bill2008Ltd replaced the top Phillips screw with a similar-sized hex head screw so he could tighten it with a 1/4 inch ratchet and socket.

The driver side

Neither thread gives a full step-by-step for the driver side, mostly because people said it is the easy one. sbr711 said to look under the driver side of the dash with a light. Tim said the last picture in his post showed the driver-side motor as seen from the driver floor. The same three-outer-screws idea applies.

The exception is right-hand-drive cars. DareDevil01, with a right-hand-drive 2008 Santa Fe that had both sides fail, found the parking brake assembly was completely in the way of the top right screw on the driver-side actuator. He got it out using a screw bit and a clamp. For him, the glove box side was actually the easier one.

Other things owners found when a new actuator did not fix it

Most people in these threads swapped the actuator and were done. A few were not, and their stories are worth knowing before you order a second part.

Low refrigerant

Owner 06lx808 had one side blowing warmer than the other with the A/C on. On his 2006 the cause was low refrigerant. He topped it off and both sides were cool, measured with thermometers in both center vents. He added that you may need the system evacuated and recharged. canderson explained why this fits: both sides are fed in common for A/C, and the doors decide the result. If the doors are moving and one side is still warm on A/C, look at the charge.

The new part was dead

Nismo06 replaced his passenger actuator with a new part from the dealer, and it would not move. He returned it, found another at a different dealership, and that one worked. This is why the test-before-install step matters.

The old part went back in

brookjt, on a 2007 Veracruz, got cold air after the swap but the driver side would not go to full heat. He pulled it back out and plugged it in, and it did not move at all. His wife was “almost positive” she had handed him the new part. Looking at the photos he took before he started, they realized he had put the old one back in. Keep the new and old parts apart on the bench.

Wiring to the actuator

DareDevil01 repaired both sides on his Santa Fe, then the driver side started acting up again. He swapped in the working passenger unit and saw the same thing, and moving the wiring made it work and then stop. He suspected the wiring going to the actuator. Nobody posted a resolution.

Still unsolved

Katja, on a 2007 with about 250,000 km, installed a new driver actuator for no A/C on the driver side. It made no difference. The actuator was getting power and she could feel it moving. She mentioned the problem started right after a shop replaced her clock spring. Tim, who started the thread, said he did not see how the clock spring would affect it unless something electrical happened. Her shop thought it was electrical and said finding it would mean taking the dash apart. The thread never says what it turned out to be.

Jrmaggie also posted that the driver side still blew warm after a working new actuator went in, with no follow-up. And sejarzo asked how many actuators a 2006 Sonata GLS with the standard, non-dual system has, since his driver vents ran 8 to 10F warmer than the passenger vents on A/C. That question did not get a direct answer, so if you have the single-zone system, do not assume this exact procedure maps one for one.

Other Hyundais the same job helped

Owners reported using these write-ups on more than the Sonata. jim4802 did a 2008 Veracruz. Bill2008Ltd did a 2008 Azera, which he called very similar to the Sonata. littlelegs and DareDevil01 did right-hand-drive 2008 Santa Fes. Ace805 did a 2008 Elantra. KentJ, on a 2006 NF Sonata, said it went very much like the write-up and he thought the pre-facelift car was slightly less crowded behind the glove box. Your part number may differ by model, so confirm it with your VIN.

My quick checklist

1. Confirm only the temperature is stuck on one side and the mode vents still switch.
2. Check coolant, the temp gauge, and the fuses, and feel both heater hoses with the engine warm.
3. Find out which side is dead. White arm for passenger, blue arm for driver, according to the forum.
4. Feel the actuator, or pull it and move the door by hand, to prove it is the motor.
5. Get the right part for your VIN. Owners used Dorman 604-310 passenger and 604-308 driver.
6. Compare guide plates and swap the old one onto the new motor if they do not match.
7. Test the new actuator hanging on the harness before you screw it in.
8. Match door and actuator to the same end of travel, seat the pin in the track, and install the three outer screws.
9. Test full hot to full cold, then reassemble and reset the clock.

Sources

Everything in this article comes from these two owner threads on hyundai-forums.com. Thanks to Hwy61, TimH3502, and everyone who added tips in the replies.

• 2009 Sonata: How To Remove and Replace the Heat Control Actuator (Hwy61 and replies)
• DIY Blend Door Temp motor / actuator with pics (TimH3502 and replies)

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