So I decided that today was the day to charge up my A/C system.

Using my trusty A/C gauge, valve and hose, I check my low side A/C pressure. Noting it to be a bit on the low side, I pull out a can of R134a refrigerant.

Notice a leak through the low side valve, no big deal I figure. Just cap it with the plastic cover, should be alright.

Biggest mistake .... I had the can resting on the hoodledge on its side (NOT UPRIGHT!!!!!!!! Arrgghhh). I think I might have sucked in some liquid refrigerant in to the low side.

Liquid R134a + low side of compressor is NOT good, because you can't compress liquid. Anyway, thank goodness I didn't lock it up.

Now here's the problem:
When I first switch on my A/C, it works fine for a few minutes, then it starts cycling on and off.

I bypassed the pressure switch to have the compressor on 100%, and it blew cold again. As soon as I hook up the pressure switch, it starts cycling again.

Any ideas before I take it to the shop? Will be back in 3 weeks from a business trip, so I will check back with the org then.

 

Suspect #1 is the pressure switch

Also, I have a feeling that my A/C compressor is working (but not optimally).

Low side pressure is about 25 when compressor is engaged, 45 when compressor isn't.

 

Or I could just need a little more charge of refrigerant?

Found this on A/C forum:
http://www.ackits.com/forum/messagev...&threadid=6200

Got the same symptoms (compressor cycles every 5-7 seconds), didn't check evap inlet temp BUT low side hose from the compressor is cold. Brrrrr.

Pressure values are also different (p.s: Using cheap gauge from A/C kit, good enough for an estimate).

 

I've done similar before. My compressor would cycle on and off and the low side hose was very cold. Ended up that I had added too much R-134, and the compressor kicks off as a safety feature (or so I've been told. Kinda makes sense, since you don't want too much pressure). The solution was to simply let some of the pressure out. I took my time doing this, letting a little pressure out, waiting, repeat. Did this until I got down to about 24 psi (according to my cheap gauges. FSM says spec is 24-27 or so depending on outside temp). Compressor acts normal, and my AC is cold. This was last summer, and still working fine. Also verified it was cooling sufficiently by using the temp probe for my digital multimeter in the center air vents on Max AC. It will get it 39 degrees F below outside temp.
Hope this helps.

Dave

 

Dave H

That does make sense, I didn't consider looking at the FSM (just moved, FSM packed in some box somewhere)

I will try releasing some pressure from the low side.

 

He's right. It's overcharged. Had the same problem on my wife's max.

 

Thanks ... will be checking it out in a couple of weeks. (out of town now)

 

If its not blowing cold, it means the freon obviously leaked out (the oil leaks out with the freon, thats why UV dye is used) and the comp is trying to save itself so dont use the A/C for the time being. There are no short cuts for A/C repair.