Yet another AC cold driver/warm middle/hot right thread

[X5Cat]

Having the same problem you originally described. It's 87F ambient temp and the unit is blowing about 60F - 64F air on the left side, but feels like ambient or even a bit like heat on the right side. Checked pressure and I've got 40 psi on the low side (35 before it gets hot, and jumps to 70 when I cut it off). I tried adding some 134a, but it won't take any. Weird. Really makes the most sense to me that it would be the heater control valve(s), but then I read your story about how adding the 134a fixed it. Confused. Thinking about blocking off the valve and/or heater core to prove if it is the valve or not. I know in other domestic vehicles for decades in the past folks would do this, and I have done it myself, too. I knew one guy who installed just a standard gate water valve in place of the heater control valve, and he just raised the hood and opened/closed the valve whenever he wanted air or heat.

[DBrown]

weasel, if i were to just clamp one of the hoses off to stop the flow of coolant due to a faulty heater control valve. which hose would i pinch? i have a 2001 4.4i
do you have a diagram, or know a link to one that shows which hoses are intake and which are not? lots of hot air is coming in because the hcv is bad and i'm looking for a temp. a/c fix.

[x5turtle]

So I guess the question now is what Low side pressure should we be looking for. Since ambient temperature dictates the low side pressure. Should we follow the pressure chart range on the freon bottle? What about adding freon after driving the car and the bay is hot, is ambient temperature still accurate or should we use infrared temperature to measure, and where to point?

[zzzzkev]

Originally Posted by x5turtle

So I guess the question now is what Low side pressure should we be looking for. Since ambient temperature dictates the low side pressure. Should we follow the pressure chart range on the freon bottle? What about adding freon after driving the car and the bay is hot, is ambient temperature still accurate or should we use infrared temperature to measure, and where to point?

There is a sticker in the engine compartment with the stated pressure. It is located on the left hand side of the engine compartment as you look at the front of the vehicle.
According to my Bentley's manual it's 440 +/- 10 grams (0.97 +/- 0.02lbs).
[Reference page 640-2, Table A, Bentley's manual]

[x5turtle]

Also, I checked my freon pressure and it was around 40 psi at 85F, so it should be at a fair level. I plugged in my BMW scanner 1.4 and it saids secondary solenoid is short, does this mean my heater core is not good?

[x5turtle]

I just added freon yesterday to the system. It fixed the whole cold left warm middle hot right issue. However, I don't think I ever got a accurate measure of the PSI. As I am full blasting the AC, and with the compressor running with ambient temperature at 88F, I have a reading of 40psi, I try giving it a couple burst or freon and PSI never moved... I gave a few more and still didn't move... so I ended up just feeling the cool air and I stop filling the system to avoid overfilling... I kept the bottle around just in case I need to give it a boost. What is your experience... am I having a bad gauge...

Ideally, should I be injecting freon on a super hot day or cooler day? Assuming my gauge is not working well.... My reasoning is to fill in hot day if I don't have a gauge to avoid the chance of overfilling in colder days when using the method of "feeling the air from the vents" What do you guys think?

[zzzzkev]

Originally Posted by x5turtle

I just added freon yesterday to the system. It fixed the whole cold left warm middle hot right issue. However, I don't think I ever got a accurate measure of the PSI. As I am full blasting the AC, and with the compressor running with ambient temperature at 88F, I have a reading of 40psi, I try giving it a couple burst or freon and PSI never moved... I gave a few more and still didn't move... so I ended up just feeling the cool air and I stop filling the system to avoid overfilling... I kept the bottle around just in case I need to give it a boost. What is your experience... am I having a bad gauge...

Ideally, should I be injecting freon on a super hot day or cooler day? Assuming my gauge is not working well.... My reasoning is to fill in hot day if I don't have a gauge to avoid the chance of overfilling in colder days when using the method of "feeling the air from the vents" What do you guys think?

x5turtle. I'm sorry but I don't know a/c. I gave you what the Bentley manual had in it. I had the same problem a few years ago and the stealer nicked me for more than 4 grand. "Had to replace the unit in the center of the dash" remove the dash to get to it, etc. Total BS. It's why I don't trust him.

[upallnight]

Originally Posted by x5turtle

I just added freon yesterday to the system. It fixed the whole cold left warm middle hot right issue. However, I don't think I ever got a accurate measure of the PSI. As I am full blasting the AC, and with the compressor running with ambient temperature at 88F, I have a reading of 40psi, I try giving it a couple burst or freon and PSI never moved... I gave a few more and still didn't move... so I ended up just feeling the cool air and I stop filling the system to avoid overfilling... I kept the bottle around just in case I need to give it a boost. What is your experience... am I having a bad gauge...

Ideally, should I be injecting freon on a super hot day or cooler day? Assuming my gauge is not working well.... My reasoning is to fill in hot day if I don't have a gauge to avoid the chance of overfilling in colder days when using the method of "feeling the air from the vents" What do you guys think?

You can go by this chart if you are adding refrigerant to the system. Normally you will remove all the refrigerant, vacuum the system and add back the refrigerant by weight.