jso2378

I am trying to charge my a/c and the compressor will not come on. I tried running a jump wire from the positive battery terminal to the compressor relay pin 87 and nothing happened. On low fan the a/c indicator light flashes and goes out. On high fan indicator stays lit but no compressor. I am trying to charge with a can of a/c pro.When I put the 134 hose on the low charging port the gauge reads the system is charged but the compressor is not running so I don't think its an accurate reading. I don't know. Should the compressor have come on using the jump method I used? Any help is appreciated.

oldchevy

Try unplugging the plug going to the receiver/dryer and jumping the 2 terminals on the cable. This will bypass the switch.

a55bruce

Jumping power to pin 87 should engage the compressor clutch IF the A/C CMPRSR fuse is good. Have you checked the connector at the compressor?
Check for continuity from pin 87 to ground, should be able to see the resistance of the clutch coil, mine measured 4 ohms.
Also noticed the relay can be inserted 2 ways, try applying power to the diagonally opposite connector. My pin 87 was the upper right terminal.

jso2378

Continuity at pin 87 reads 0.5 ohms. Also have 0.5 ohms on both sides of the compressor fuse. However when I checked voltage at the compressor fuse I got a -0.2 reading on both sides. A test light confirms I have no voltage at either side of the fuse. The compressor wires are plugged in.I am wondering if its a ground issue. I bought the car wrecked at a auction (ex police car) and repaired it. When I first got the car it had no power to anything. Found the big ground wire in front of the battery on the core support was disconnected.

a55bruce

The fuse only has power if the compressor relay is closed/energized.
0.5 ohms sounds too low. Were you measuring the continuity to the clutch connector? What resistance range where you using on your meter?
My 4 ohms was measured from pin 87 to chassis ground. Which tells you that the clutch circuit is OK.
You should be able to hear the clutch click when you apply power to pin 87, you can do this with the engine off.
Check to see that you have power on pin 30.

jso2378

Was using 2000. Retried it, continuity to pin 87 and kept flickering from 5-6.I ran a jumper wire from pin 30 to 87 and the compressor came on but a/c power light inside still flashing. Should I leave the jumper wire in place and try charging the system?

jso2378

I tried charging the system with the compressor jumped and running. It was already fully charged and needed no additional 134. With the compressor jumped it is still blowing hot air from the vents.When I pull the jump wire and reinstall the relay compressor will not come on. I tried replacing the relay with another one and compressor still does not come on.The a/c power light will stay lit if fan is on high but flashes when fan speed is reduced. Something I did notice is the engine cooling fans never switched to high speed but then again the engine temperature was normal the whole time.I am lost and have no idea what to try next.

tech2

the ac system can set powertrain and body codes...any code set?

jso2378

No check engine light illuminated. Will check for codes this afternoon.

tech2

body codes won't set the mil. full function scan tool required to retrieve body codes. cheap code readers won't cut it.