Need basic A/C info

[hertfordnc]

2001 Expy with rear air .

Last winter we changed the AC compressor due to a bad bearing- AC system was fine.

This week i finally got around to recharging it. i vacuumed it down, added refrigerant- it has pressure. does not clutch in.

Obviously there could be many things wrong but I just want to now about things related to changing the compressor and recharging an empty system.

Just because i do this work myself doesn't mean i understand it.

 

[stamp11127]

How much pressure on low side? There needs to be at least @25-29 psi to close the low pressure switch so that the compressor clutch engages. Usually there is more than enough pressure in the bulk bottle to do this.

Also how long did you pull a vacuum and what was the gauge reading?

A/C 101:
The system absorbs heat from one area and discharges it in another. This is accomplished through a state change of the refrigerant. In the evap it changes from a liquid to gas by absorbing the heat of the interior. The compressor then moves the gas into the condenser under pressure where it changes back to a liquid by discharging heat. Then the cycle repeats. Other parts of the system have been left out to keep it simple.

 

[omegalita]

Think this is the selenoid from the compressor. Had this also on mine...
You can order this as one seperatepart and fix it.

You can proof it with 12V directly on the compressor. If it clutches in, its ok, other problem. If it clutches not in, you've found the problem....

 

[hertfordnc]

I have over 45 PSI on the LP side from only one can. It's a rear AC system so i know it will take a lot more.

I don't have proper vac gauges but i ran my cheap little 1.5 CFM vac pump for several hours and then confirmed that it held vacuum overnight.

The compressor solenoid could be bad but the compressor is new and all was working when the compressor bearing went out.

Also, what's the trick to removing the connector on the compressor? I can't figure out where to squeeze or pull or pry.

 

[hertfordnc]

I found the problem- DUH, either I or my son-in-law (who had the truck over the winter) borrowed the AC clutch fuse. It was missing. All is good.