heater control woes *searched*
 

so I picked up this 05 back in august and have been having problems with the heater.

i searched this issue and its been helpful but problem isnt fixed.

basic issue is temp knob doesnt work. when i bought the car, it was stuck on full hot.
the range didnt move so figured it was dash pots.

soldered them as per the diy and reinstalled the unit. showed it had full range but now it only blew ice cold air. so it went from pure hot to pure cold and the display showed i had full range.

bought a new unit from a member on here and installed it. shows full range but still stuck on cold.

at a loss. not sure why it would say its working but has no difference on temps. i thought for a moment that maybe it was the flapper or controller on the heater core itself but i didnt mess with that stuff at all when messing with the switch so i dont know how it could be randomly selected to cold from hot.

anyway. anybody else have any ideas on what the issue is or what i should trouble shoot next?

thanks for any help

love the car otherwise.

Everyones first reaction is the control knobs and most of the time that is the problem. There is however hardware that moves after the electronic input from the control knob. Look under the drivers side dash directly behind the radio. You will see a white wheel ( for lack of a better description). When you turn from cold to hot or vice versa this wheel has a small rod attached and should move. If it does not, then it's possible that there is a problem with the assembly back there. I am not sure about the 8's but every vehicle I have ever had was vacuum controlled, so I am going to assume the same in this case. If you discover that is the issue, I believe the dash has to pulled to replace those parts. If you go there, I recommend replacing the core and a good coolant flush while your in there. Good luck, hope this helps.

i would be more inclined to believe that this was the case if it was not so related to the knobs. it was stuck on full hot and miraculously went to full cold by changing nothing but only the control unit.

i will look into it and probably will rig the valve open for the winter and retackle this issue in the spring.

if anyone has any other ideas or suggestions, i do keep tabs on my threads.

thank you

1. Set the heat to 100%.
2. Start the car, or at least turn the key till the fan/HVAC engages.
3. Get a flashlight, bright one, and look straight down the passenger side center vent (just above the radio).
4. As your looking down the vent, turn the hot/cold knob from 100% hot to cold.

What you should see is a flap moving as you turn the knob. At 100% one way you should see what looks like a mini-radiator (hot I think). At 100% the other way, you should see the foam flap.

If you turn the knob back and forth and never see anything move, it could be the motor that controls this flap.

There are two locations to watch for moving parts. One is under the driver side dash (yes, crawl under there and look straight up with a good light). The 'white wheel' will be found here. This wheel moves as you cycle through the different vent modes (front, windshield, feet, etc). I believe the other one is behind the glove compartment near the top of the dash (i.e. behind the radio), which controls the hot/cold flap.

If all of these check out (everything moves, hot/cold flap is working), then you could check the heater core outlet pipe.

Beside the washer fluid reservoir are four pipes going through the firewall into the cabin. the top right pipe is "Heat-In". The bottom left pipe is "Heat-Out".
- After the engine is warmed up, turn off the car and check the pipes (careful they could be very hot).
- If the "In" pipe is hot, and the "Out" pipe is cold, the heater core could be plugged.
- If the "In" pipe is cold, the thermostat might be faulty?
- If both pipes are hot, then your heater core should be getting heat.

Try those things for now and see where you get.

i looked at this again a few weeks ago. the rod that actuates the flap is missing. someone has disconnected it. it was dark and late so i didnt try to fix it beyond flipping the flap. car now has full heat till i can get back under there and find the rod and reconnect it. id be more inclined to work on it if i needed to drive this car more than 5 miles a week

I'm having the same issue. I solder the three pins but still have only cold air. I tried looking trough the vents and saw something moving when changing vent modes but nothing moves on the passenger side when moving from hot to cold. Which rod are you referring to? where exactly is located? Do I need to remove the radio? Thanx.