95 525i AC Problems

1995 525i
106,000 miles
Being driven in Chicago in mid 90's temps

Compressor, evap, condenser, dryer replaced with new components, system evacuated and recharged with proper amount of 134. High/Low pressures within specs. Problem: repair shop gets 45 degrees F at the dash vents with fan on Low (speed 1). As you increase fan speed, vent temp rises. Speed 2 is around 60 deg, speed 3 around is around 70, and High is 80+ deg. I have also noticed this - With the vent slider controls set as follows - top slider full left, middle full right, bottom full right - and the temp controls both set to lowest possible temp, I get warm air coming from floor vents. Coolish air from the dash vents, warmish air from the floor vents. Lowering a window while driving seems to make this problem worse. Setting the top slider full right gives full on heat to the windshield (again, with temp controls set to coldest setting). Could it be the water valves on the heater hoses, microfilter clogged, sensors?

Repair shop thinking it might be a problem with the HVAC control panel on the dash. Sensors? Engine cooling fan is working correclty.

Has anyone every had this issue with their beloved BMW? Any ideas or suggestions are very much appreciated. Thanks for the help!

clogged micro filter will restrict airflow not warm it up, heater valves could be dead you can check that with a hose pincher or needle nose vicegrips on the common heater hose (two in one out or one in two out i can't remember) if the electric fan is not working that will seriously kill the cooling capacity of the ac, if the compressor is comming on and the evap is not turning into a block of ice and the air comes out the vents you want the hvac panel is doing it's job. it's normal for the air temp to rise a little when not moving and at a high blower setting but not to that degree

with my old E32. About a week before I sold it I decided to replace the heater valves on the firewall by the fuse box and the A/C was the coldest it had ever been, even when it had R12! Seems that the heater valves will "leak" hot water into the system under the dash and will neutralize the cold air by mixing with it. If you've double checked everything else, I'd check them for sure.

Paul

Thanks for the help. I ordered a new valve today and hope it will solve the problem. Hope to make the repair by mid-week. Did you also replace the "auxillary pump" pn your BMW, along with the valve? I found some info on this website about replacing the valve and it referred to an auxillary pump that is attached to the valve.

Repair Update: Replaced the water valves this morning. It did improve the temp at the vents significantly throughout all fans speeds. One issue still remains however. Of the center vents (just above the radio), the right side vent (passenger) does not blow air as cold as the left side vent. The left vent is cold, the right is cool. Is this a problem with a mixer door not closing all the way, or maybe a sensor that is located in the HVAC control panel? Any help is certainly appreciated. Thanks!

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Originally Posted by CBC

Thanks for the help. I ordered a new valve today and hope it will solve the problem. Hope to make the repair by mid-week. Did you also replace the "auxillary pump" pn your BMW, along with the valve? I found some info on this website about replacing the valve and it referred to an auxillary pump that is attached to the valve.

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The aux pump primarily get warm coolant to the heater core quicker so that you have heat in the cabin sooner. Nice feature in cold climates, but certainly not necessary elsewhere. Not sure about the "cold", "cool" vent issue, whether there are stepper motors controlling the center vents separately or not. Of course, you've messed with the airflow vent "wheels" to rule that out? Also, my car has a center "mixer" that apparently controls or finetunes the amount of cold vs. warm air coming out the vents. I don't notice much difference though. Sounds like the water valve replacement did the trick, though!

that thing works great with the heater when the car has been on the road for around 20 minutes, the same for the independant controls, the mixer doesn't really do anything for the ac

Quote:

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Originally Posted by JonE

my car has a center "mixer" that apparently controls or finetunes the amount of cold vs. warm air coming out the vents. I don't notice much difference though.

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Hey there CBC funny you should mention this. I have as the board is aware been struggling with the exact same issues. I have since replaced the sword, checked the a/c panel, had the a/c system regassed and confirmed that everything is in order. I have to still do the heater valve the one i renewed seems to have been a dud, and i will hopefully also have the same success. Side note here is that i was told that incorrect a/c gas levels make the air uneven at the front vents, but then u have had this attended to. I do not think its the sword as i have had mine replaced with two other units to double check, if u figure it out please let us know,