Air Conditioning Problem

[adam3]

I have a 1990 325is

My problem is with my A/C, It works at first then doesn't work at all or is only cooling at 70 degrees. At first when the car is cold I'll start the car turn the a/c on it blows at 45 degrees or so. nice and cold.Then I"ll go to the store 20 min. drive get back in the car,start the car and the a/c will not get colder that 70 or 75.this is very consistent. It blows very cold as long as the car has sat overnight and is a cold start

Any help would be appreciated
Thanks
Adam

[coolbear1]

If you could tell me the suction (low side pressure) I could point you in the right direction, but based on the information you gave. It is a little low on refrigerant. .

When you start the car cold, the a/c system has very little load. What refrigerant that is there is just enough to cool down the evaporator initiallyon start up, but when you start down the road there is not enough refrigerant to operate at full load so it stops cooling.

The 1990 is an e30 if I remember correctly and it has a receiver drier tank mounted between the fender and the front wheel behind the passenger headlight.

If you look closely, you should find a small glass in the top of it. When the system is charged properly it wiil be clear (no bubbles) whenthe compressor is operating at full load.

Yours probably is clear at first and starts to bubble when you rev the engine , or take it for a drive.

This would indicate a low charge situation.

If you put refrigerant in it yourself, be carful not to overcharge it. You could kill the compressor, and theoretically yourself.

[adam3]

Thank you coolbear1

That would be nice easy fix...it hasnt had a recharge since converting it to R-132. I'll check the glass for bubbles. I dont have any way to give a pressure level

adam