Help on '94 Firebird Formula bad A/C - FIXED!! Thx!

[BlueValk]

My wife's a/c just quit the other day.  The clutch on the compressor will not engage.  If I hot-wire the clutch, the a/c seems to work just fine.  The pressure on the low side starts at about 100 and goes down to about 35 (which is correct on the gauge).

It has a high pressure sensor that turns the fan on and seems to work fine.  But, I can't find a too-low-pressure switch at all.  Even if the system is a bit low on R134a, it seems like it should at least try and start.

So, the a/c seems to work correctly if it would just come on.  Any ideas?
The car has 62k on it. 5.7L

TIA,
BlueValk

[Dogg]

sounds like its just a tad low on refridgerant...

[Smokinjoe-VRCCDS#0005]

sounds like its just a tad low on refridgerant...

Thats my guess also ...You can get 134 anywhere for about $8.00 a can and the hose to install is another $ 10.00 or so ...Not a bad price to pay for A/C.

[Mr.BubblesVRCCDS0008]

Low pressure switch should be on the accumulator or the line going to the evaporator. You can bypass it by jumping a wire between the terminals. If it is bad you can remove it without losing charge as there is a scraider valve under it.

[Robert]

Unfortunately it may not be that easy there is a temp sensor in the evaporator inside the car all the connections go through the pcm and that activates the compressor through the a/c relay. there is a fuse #12, I think that actually powers the compressor clutch and relay. The a/c compressor relay is marked b and its under the hood in the fuse panel there. If it has a diagram on the side I would jump it and that will tell you if you have power to the relay and to the compressor because when you jump it the clutch should engage. If it does then you have either a switch or control unit problem, which could be the temp switch or the compressor switch on the control panel or even the pressure switch. There is only one pressure switch in the system that does both high and low pressure. It has a 5v reference signal that should be a gray wire a pressure signal the wire should be red/black and of course the black that is the ground. The entire system can be checked with a scan tool not obd of course. The ideal pressure is 40/low 225 > 250/high and I don't think the system will cut the compressor out till 20 or 25 psi so I really don't think that low freon is the culprit. Last but not least if there is any kind of code in the computer it may stop the compressor from coming on. To erase them I think you can just disconnect the battery and all the stored codes should disappear. I would do this first.

[laserpat]

Try wiggeling the ac cluch connector with the ac on and engine running (Carefully) I had one with a broken wire at the connector.

[BlueValk]

Thanks for all the responses.  Robert, you've got a heck of a memory (the wire colors and the #12 fuse).  Anyway, disconnecting the battery for a while did it.  The a/c is up and running! 
It's too hot here in NM to not have a/c.  And the car is too nice still for the clunkers trade.

Thankyou, thankyou, thankyou!

BlueValk