'99 GMC Jimmy (S-series) AC Troubleshooting

[Caver Dave]

Trying to help a coworker (single mom) with her 16 y/o daughters "new" ride. Supposedly needs an AC compressor, but the PO passed away so not real sure where that diagnosis came from & I'm not very "AC" savvy & need a hand!

I took a peek at it Friday and found these symptoms:

- When setting the controls inside, nothing happens
- When jumped, the compressor clutch energizes and spins the compressor, but zero change in either the lines temp or in cab temps after 10 minutes running.

IIRC, being too low/high on refrigerant will cause the switch(es) controlling the compressor (outside of the cabin controls) to stay open?

Any tips/pointers for the newb in me?

Or is it worth the price ($10-15) to try dumping a can of 134 in it to see if that does anything (works/improves/shows the cause of a leak/etc)?

 

[moldman05]

Probably no freon,but it was replaced with air which has moisture in it. The first thing todo is pressurize system to find leak. This can be done with freon, nitrogen, or air. If leak can be located and repaired the filter/dryer/accumilator should be replaced, then evacuated with pump to remove air and moisture. Then you can fill system with proper amount of freon. If air remains high side pressure will be to high and moisture will freeze and block freon flow(no cooling)

 

[Stuntman Autoworks]

Yeah I would bet you have a leak somewhere the compressor probably isn't running b/c the freon is low have the system vacuumed out and theres really no way to find it other than recharging the system and injecting some dye to find where the leak is then go from there.