AC Problem = Heater Control Valve?

Hey,
I am having a problem with my AC which I think I've narrowed down to a faulty heater control valve.

When I turn my AC on it blows ice cold in the middle vents, but super hot out towards to windshield and my feet. I read that was the heater control valve.

Has anyone replaced it? Anyone know of a DIY online? How much does the part cost? I searched bavauto but they didn't have anything online and realoem.com was just too daunting.

Any help is appreciated.


-Justin

The valve is easy to replace.

I bought a BMW valve at CarQuest for $66.

Begin by removing the air filter box and intact tract down to the throttle body. From there, you'll see the valve on the inside of the driver side fender. Two heater hoses go into the valve and there's a 2-wire connector that goes into the valve. If you want to avoid draining the cooling system, use a pair of vise grips to crimp off the heater hoses going to the valve. Undo the clamps on the hoses and pull them off. The valve is mounted by rubber grommets and simply pulls up and out. Installation is reverse of removal.

My AC was acting up and no fix after the dealer and a shop looked at it. Simple fix....and even if it doesn't fix it, it's a pretty cheap parts swap.

what was your ac doing to have to change this part and do you have any pitures or partnumbers for this part. I m glad you got it working just let me know some extra detail.

Originally Posted by shall36

The valve is easy to replace.

I bought a BMW valve at CarQuest for $66.

Begin by removing the air filter box and intact tract down to the throttle body. From there, you'll see the valve on the inside of the driver side fender. Two heater hoses go into the valve and there's a 2-wire connector that goes into the valve. If you want to avoid draining the cooling system, use a pair of vise grips to crimp off the heater hoses going to the valve. Undo the clamps on the hoses and pull them off. The valve is mounted by rubber grommets and simply pulls up and out. Installation is reverse of removal.

My AC was acting up and no fix after the dealer and a shop looked at it. Simple fix....and even if it doesn't fix it, it's a pretty cheap parts swap.

I had the same (or similar problem) a while back, I researched for a long time but never heard of the heater control valve? I brought my car in for some work (required a reflash and some recalibration on other stuff) and the problem was gone. No clue what they did but absolutely no part related to the heating/cooling system was changed.


Just curious, does you temp gauge ever show the car underheating?

Originally Posted by black323i1981

what was your ac doing to have to change this part and do you have any pitures or partnumbers for this part. I m glad you got it working just let me know some extra detail.

Part number is 64118369805. They call it a "Hvac - Heater Control Valve". It is $59.80 from Tischer BMW.

My system would cool intermittently but the compressor was operating telling me that this wasn't a leak or refrigerant problem.

The dealer's diagnosis was a leaking evaporator and they wanted $1,500 or something stupid like that to replace it.

Took it to an indy shop and he could not find a leak. So, he put dye in the system and checked it again in 500 miles. No leak. The problem still persisted and he changed a pressure switch on a hunch. No joy...still intermittent.

The water valve seemed to do the trick.

The way the automatic AC system works is that the compressor runs and cools the evaporator core in the cabin. The blower blows air over that cold evaporator and cools and dries the air. When the cabin gets too cool, hot engine coolant is allowed to flow into the heater core. Air that has just been cooled by blowing over the evaporator core now also blows over the hot heater core. The water valve is a plunger valve operated by a solenoid. The heater core temp is regulated by opening and closing the valve.

I did an autopsy on the valve. The plunger worked fine and sealed tight. The solenoid functioned when energized. What I found was coolant has seeped up into the solenoid and I suspect that was allowing the valve to stay open (default position).

Is there a way to temporarily close the valve until I have time to do the switch?

You could leave a vise grip or clamp on one of the hoses.

Can you tell me which hose it is? or do you have a picture? It won't harm anything to clamp it off?

I clamped mine for last summer, don't vise grip anything. I had a custom clamp made with padding, you don't want to damage a hose over the long term!


You clamp the outlet hose of the water valve, thats what stops hot coolant from flowing to the heater core. Look at the heater/air conditioning and then water pump, valves, and hoses section of realoem for your car.

The valve is on the driver's side inner fender. There are two hoses going into the valve. They're about 1.5" or so in diameter...can't miss them. The easiest way to clamp them off would be to use a small pair of vise grips (the needle nose type would probably work best), wrap the hose in a rag (to keep the serrations of the vise grips from digging in), and clamp down enough to keep the vise grips on. Cake.

Originally Posted by jraine

Hey,
I am having a problem with my AC which I think I've narrowed down to a faulty heater control valve.

When I turn my AC on it blows ice cold in the middle vents, but super hot out towards to windshield and my feet. I read that was the heater control valve.

Has anyone replaced it? Anyone know of a DIY online? How much does the part cost? I searched bavauto but they didn't have anything online and realoem.com was just too daunting.

Any help is appreciated.


-Justin

Ok I just changed my HCV today and it was a pain since I had to move some parts of my super charger. But for you it is real easy to remove the air intake and then pull up the HCV and loosen the 2 hose clamp and electrical plug. Then replace and do the reverse steps. Some coolant will leak out but just top it off afterward.

Well, all this work and still didn't fix my AC problem I had already change out the final stage resistor and had the AC recharged and dye test prior to the HCV. There was no leak that can be found. My problem is when the AC auto is on, it blows warm air in the middle vents and slightly cold on the driver side and passenger. If I put just the feet, its hot as heck even with AC fully blast at 59 degrees. Its also the same when I have just the windshield on. If I have the face and windshield then its hot up top and warm at the face. But when I have the feet and face on then the face vents are cold but the feel is still hot.... WTF. Does anyone else know what I should check out next?

could you not just disconnect the valve and put the hoses together with a union and see if thats the problem that way? Bypass the valve all together instead of changing out parts.....

Originally Posted by GermnBlt

could you not just disconnect the valve and put the hoses together with a union and see if thats the problem that way? Bypass the valve all together instead of changing out parts.....

Yes, I guess I could of but thought it really was the problem. Oh well, I got new water valve anyway it wasn't to much $$$ compare to my other mods lol. I want to change out problem parts so later I don't have to worry about it. Now I just have to figure out what else it can be before I take it to the stealership Any suggestion???

what about the damper door behind the cabin filter housing? Are you running the car with the cabin filter housing or running without it?

Originally Posted by GermnBlt

what about the damper door behind the cabin filter housing? Are you running the car with the cabin filter housing or running without it?

I have check that and the door and blower all work. I have also swap out the climate control display with my friend and still didnt fix. I don't think its the flapper doors under the dash cus when I put the feet only it blows there, and face same thing and dash too. So it seem to be working right for all settings. I just don't get why it blow hot at the feet but when I put both face and feet, the face is cold and feet is hot

hmmmm.....somethings allowing heat in or not working to allow cool.....interesting.....have you had anything done to your dash that may have done this without knowing?

let me tell you what mine does.........Anytime you drive the car? The air gets cold, but when your sitting at a stop light or train or just idling? It heats up basically to HOT....Then once on the gas again it cools...I thought it may be the hcv...I by passed it and its still doing the same thing...any ideas? I just had one of my hoses replaced by a indy and they recharged it to the correct amount of gas..im puzzled

I have the same problem... Hot at the feet cold everywhere else. Could the recirculate have anything to do with it? How do you check the vent doors?

Ok I try again swapping out the AC control with Tas since he got same year as mine. This time we confirm its not it cus mine works in his car but his don't work in mine. He also notice that my fan whines very loud and that my dash outside temp was not the right temp. Mine was like 10 degrees hotter then his. Does anyone know if these added info has to do with my AC problem? Anyone else know what I should check out next? I know the outside thermostat is in the front bumper area. Anyone know where the thermostat is located inside the car for the interior temp so the climate control knows how much to put out?

TIA,
Charlie