a/c only works at nite

sillypsyben · 07-25-2004, 03:38 PM

This is my first time posting in here, and all the information in here is greatly appreciated. Its been alot of too me an others aswell im sure, thanx.......So to the problem at hand. I have a 96 328i 4dr. over 115k mi. I had just replaced my a/c condensor because the a/transmission lines rubbed a hole in 1 of the cores, which i fixed when i installed the new one. So after installing and charging the system (stuff used by Pepboys to charge3 cans of r-134a and 1 can of esther oil) the registers inside the car read about 57 degrees idle; so i finished and cleaned things up then took it out for a drive. 5 minutes into the drive i noticed it started to switch on and off i could tell by the power of the car and it started to get warm inside so i took it back home to check things out again and couldnt find anything (by the way this took place in the afternoon in AZ. at the begining of July) after i was done double and triple checking things out it was after dark. I decided to take it out again and hope for the best so i took a cruise for bout half an hour w/ac on and no trouble what so ever. To make a longer story short, during the daytime the a/c wont work after dark there seems to be no trouble.......So if you guys can be of some help? thanx Jason

Jared at Pelican Parts · 07-26-2004, 08:14 AM

Did you have the system evacuated prior to charging it up?

Did you replace your reciever drier?

sillypsyben · 07-26-2004, 09:07 PM

no, i did neither.There was still some pressure although not alot in one of the lines....but that probably doesnt mean a thing, so should i have it evacuated and replace the drier.I was told that the drier didnt need replacing because it was an outward leak and i didnt have any trouble prior to the hole rubbed into the condensor. That statement was made from a tech at Sports car Recycling which mostly deals with BMW's; so i took his advice.

Jared at Pelican Parts · 07-27-2004, 07:29 AM

If you replaced the condensor, you opened the system up to outside air, which means all the pressure inside would be lost. You have to evacute (suck out) all the air in the system prior to charging. This is done by using a vacuum pump. Once this is done, you can then refill.

The reciever drier should be replaced anytime you open the system up to air as well.

ghostnova · 07-29-2004, 06:40 PM

You probably have some extra r-134a ester oil remaining from the previous refrigerant installation. If this remains you won't be able to get the correct amount of r-134a into the system and your performance will drop. Also, as Jared said, basically you MUST replace the dryer when you open up thge system. the desicant in the dryer will immediately be contaminated if exposed to open air moisture for any exteneded period of time (like when you changed the condensor).

I would evacuate the system with a vacuum pump, put a a new dryer in, then recharge. Make sure you review the guidlines in your owner's manual for the correct amount of ester oil and r-134a. Then make sure your low and high side pressures check out with manifold gauges. Otherwise, check the low side with a decent gauge from the autoparts store.

I did a retrofit to r-134a on my Acura Integra a month ago and it blows at high at 41 F. Be meticulous with AC work and it will work well for you.