GM Mechanics...Need help w/ 99 monte carlo

[mudbog42]

Ok well here's the deal, trying to get a/c working again on my 99 Monte Carlo (3.1l).

When I check the system pressure it shows that it is full , but the compressor clutch does not engage. So I jump 12 volts the compressor and it engages, so compressor and clutch are good I'm assuming.

I checked the HVAC fuse and its good, then I replaced the a/c relay and still nothing, so I figured it has to be the pressure switch...well just replaced it and still no go.

Even with clutch engaged though, it doesn't blow any cold air and the lines under the hood don't even get cold.

I can't seem to figure this out, any help would be greatly appreciated

Thanks

 

[84zz4ss]

Full? What are the high and low static pressures?

 

[mudbog42]

Actually I should re word that, It just shows that it is overcharged with those cheap little gauges that come with the freon cans from the parts store, I believe it was reading 105 or 110 PSI, and it doesn't change if I jump the compressor clutch to kick on, it still reads the same.

 

[chevyuser74]

u should suck it out, evacuate it and recharge it, probably take care of the problem especially since your pressure switch wont kick in the compressor. pressure is only an indicator not a way of telling if a system has enough refigerant in it.

 

[mudbog42]

Hmmmm...Should I take that new relay and pressure switch back, since they were kind of expensive or just leave them in as preventative maintenance...

 

[chevyuser74]

if they werent that much id leave them alone, if not and u know they will take em back return em, just so u know, ive never had to replace the pressure switch or relay on a monte carlo so i dont think they have problems with em at all

 

[mudbog42]

Well I took them back off and am going to try and return them and then head over to the machine to do as you said.

Hopefully it works

 

[wasted wages]

I believe it was reading 105 or 110 PSI, and it doesn't change if I jump the compressor clutch to kick on, it still reads the same.

If I read this right you said there is no pressure change when the clutch is engaged and the compressor is spinning,,, right ??

If that is the case,, then the comp. is shot,,,and not pumping ...

 

[chevyuser74]

the pressure switch is not kicking it in to begin with he powered it on manually

 

[mudbog42]

Chevyuser74,
You were absolutely right, I put the old switch and relay back in, hooked it to the machine, and it only had .08 lbs of freon in it (should have 1.88), when we sucked it out.

Vacuumed the system, replaced the little valve stems, refilled it and it blows cold as ever.

Thanks for the help

 

[chevyuser74]

no problem.