97 A/C problem

I picked up my PA recently from a girl at work. The engine was ruined on a trip down the interstate with little or no coolant. I got the car and found a salvage yard engine with 70K and everything up front runs fine again. Once it warmed up I realized my compressor clutch isn't engaging when I'm selecting cool. This is the first car I've run with the climate control feature of the PA so I went through all the keypad buttons and they respond correctly as far as fan speeds & air direction.Selecting defrost doesn't engage the compressor either so I evacuated the system and it held good vacuum for approx. 30 mins after the vacuum pump was shut off. I got 24 ounces into the system by jumping the clutch and unhooked my jumper wire hoping the system would take over on it's own to finish the freon charge but the clutch won't engage.I've verified the underhood fuses and relay are good and the fuses in the R/H fuse box are good(is that all the fuses).I don't have a problem tearing into things to check switches or sensors I'm just new to these vehicles and need some direction. By the way the 2 white buttons on either side on top of the dash, one seems to be missing a cap or something, they don't look the same.From reading other threads I need to get the glovebox out so I can watch the actuators. The vehicle set for about 4 months between the time I got it and put the new engine in. The battery has gone dead & been disconnected several times. Also the folks that owned it previously bragged on how good the A/C worked before the problems with the engine. Sorry about the long winded thread.

I would say that the compressor is toast. When my compressor went out on my PA I tried to charge it and at first the compressor clutch did cycle on but it wouldn't take much refrigerant and still wasn't cooling. Then I let the refrigerant out and tried to charge it again. The refrigerant wouldn't charges and was coming out of the low side charge fitting. Long story short I got a new compressor with the usually orifice tube and accumulator. Then I found out that my compressor committed suicide and puked metal shavings through the system. So I had to get a new condenser, and flush the system out. Now she's back to blowing ICE COLD air like she used too. Also those two white buttons may be the sunload sensors without the cap.

I'm not sure I want to go the new compressor route just yet. I'm not getting voltage to the clutch which needs a ground signal from the PCM to close the A/C relay. What I need to know is the sequence of events that occur before the PCM decides to close the A/C relay but thanks for the reply.

It uses the pressure switches in the ac lines, too high or too low will prevent engagement.

Is the climate control display flashing? If so you have set a low charge code- unhook battery for 10 seconds to reset the PCM....

maxwedge-I hooked my gages up again and only had 40psi static pressure on both sides. I only see 1 pressure switch with 3 wires so I guess it's a binary switch for both high and low pressure. What would be the minimum pressure for it to operate ? When I put an ohmmeter on the switch,the grey wire(5 volt input)and the red wire show resistance and the greyto black are open. brcidd-no flashing display that I recall,does it flash whatever mode the display is showing? Like outside air temp, fan location etc.

the display will flash when you first start the car and will go away after a minute or two.

I too am having the same prob..no juice to clutch but when jumper'd she will freeze me out. Can the clutch diode be bad and how can you check it....I am going to try checking the PCM signal to relay today but im pretty sure relay is good, well let all know:screwy:

The past couple of weeks I've been chasing leaks in the system. I can still charge the A/C with my jumper wire set-up but now the green wire at the clutch is showig voltage all the time the battery is hooked up. I was probably on the wrong side of the connector before. When the key is on I have voltage in 1 side of the control circuit and both sides of the power cicuit without the relay installed. Now I'm really confused.