A/C acting up again.. weird problem

[gensic11]

Ok I just had my A/C fixed at Midas recently due to Low Pressure in the system. They added about 2lbs and it was running perfectly. I used to have the problem where the compressor would kick on and off. Anyway here's my new problem.

When I am driving, the compressor works perfectly (does not cycle out of control). But, right when I stop - the compressor starts cycling like it was low on pressure again. I don't understand because when I drive, I am still getting cold air coming from the vents. Last time my compressor cycled was because I had low pressure and it wouldn't blow out any cold air.

What could be the cause of my compressor wanting to cycle every 3 seconds when I come to a stop (say at a red light)? I have read some things about a pressure switch possibly going bad.. does this sound right?

Any other suggestions? I haven't checked under the hood yet for a major leak but I am still getting cold air - so I'm sort of stumped as to why the compressor would work fine while driving - yet not work right when idling..

 

[Turdle]

I just recently changed my accumulator bottle, and have an extra pressure switch. You can have it to try if you want it. no charge. I save things for you guys lol

 

[gensic11]

i might take you up on that. i am getting it checked out for free today at midas since they worked on it a month ago.. if it ends up being the switch then i'll probably take yours if they decide to charge me a lot.. how much was it for you to change your accumulator? was it a DIY job? it seems like it would be a simple job..

 

[shamaal]

Let us know what you find out at Midas, I'm guessing a slow leak.

My take on what's happening.
When you drive the car, air flows over the condensor causing more of the high pressure gas to turn to liquid. More liquid reduces overall vapor volume (liquid is noncompressible) and increases pressure differential.

With the type of A/C system we have (fixed orifice) there is a difference in performance in hot weather between driving and stationary. Design should be adequate that chilled air is available, but effiency will drop.

Switch may have an impact (it's the same switch driving or stationary). Accumlator problems include saturation (drop in efficiency) or actual degradation of the media gunking up the system. Repalacement of any A/C component is a DIY task, the challenge is in the subsequeny evacuation and charging of the system.

 

[gensic11]

ok well i went to have it checked out and they couldn't find a single problem. no leaks whatsoever and the compressor would not click on and off.. i tried to get it to do it when i left and i couldn't. OF COURSE that would happen.. his only guess was the pressure switch could be going bad - he tried to wiggle it and get it to mess up but it worked fine.. a/c was blowing cold and so there was no way to diagnose. he said something about due to the temp being over 90 degrees that could be part of the problem (i forgot his reasoning because i wasn't really listening by that point).. anyway everything seems to be working fine.

i do have one question though - if i were to remove the "blanket" on the accumulator - would that cause problems? or should i just keep it on. I know the blanket holds in moisture so i was curious if anyone has removed it because of that

 

[Turdle]

I mentioned earlier I had replaced my accumulator, it was for that very reason. A small pinhole had developed under the foam.
The new replacement had no wrap. I am at a loss what to do also.
Do you want this switch--for giggles?

 

[gensic11]

haha well i hate for you to go to the trouble of sending it and giving up a perfectly good switch if mine is still working.. but if you have no use for it then sure why not! you sure it's the same switch?

 

[Brock94]

I don't understand, it's cold right? It's probably just cycling normally. You may only notice the cycling when you are sitting still because you can't hear it when you're driving.

 

[gensic11]

no - it's different. it doesn't happen all the time and i can't figure out why it decides to do it and at what points.. all i know is it's not supposed to cycle every 3 seconds when idling.. and i know it doesn't cycle that much when i'm driving.. it doesn't always do it either.. only sometimes.