basic a/c question????

[RRROBB]

Mt 1977 has not had a working a/c for a while. I have added the newer style blower motor and cage per advice found here. Had the system vac'd down and when I went to install R134a the compressor would not engage. What can I check to see where the problem lies?????

[photovette]

Make sure the compressor clutch is getting power--if not, follow the wire back to the low-pressure cut-out switch, then to the blower relay. Should be one of those two things unless the wire is broke some where along the way.

Also, the compressor will not engage until you've added enough refrigerant to raise pressure above the low-pressure switch setpoint.

[vettepilot]

Originally Posted by RRROBB

Mt 1977 has not had a working a/c for a while. I have added the newer style blower motor and cage per advice found here. Had the system vac'd down and when I went to install R134a the compressor would not engage. What can I check to see where the problem lies?????

Did you partially charge the system first? The compressor clutch will not engage if the system detects a low head pressure. I don't recall the actual capacity of those old systems, (or the new for that matter), but try blowing about 2/3rds of the system's refridgerant capacity in before trying to run the compressor. It will go in under it's own pressure on the low side just from the can's pressure.
Then start the car and turn on the A/C, if the compressor still doesn't engage, there was a thermal fusible switch that protected the compressor when the refridgerant was low. It can be bypassed with a jumper, if the compressor then engages you need a new one. I cannot for the life of me remember what that thermal fusible switch block is correctly called, if you have a manual it may say. It may in fact be "thermal switch".....


vettepilot

thermal nuclear protectant switch?..actually you're correct. general parts term was a/c thermal switch

[vettepilot]

Originally Posted by Robin7TFour

thermal nuclear protectant switch?..actually you're correct. general parts term was a/c thermal switch

thermal nuclear protectant switch....

Thanks for the help Robin7TFour, CRS is running strong this summer......
... and me without a repair manual, and poor memory to boot, bad combo

vettepilot

[brusso]

Originally Posted by vettepilot

Then start the car and turn on the A/C, if the compressor still doesn't engage, there was a thermal fusible switch that protected the compressor when the refridgerant was low. It can be bypassed with a jumper, if the compressor then engages you need a new one. I cannot for the life of me remember what that thermal fusible switch block is correctly called, if you have a manual it may say. It may in fact be "thermal switch".....


vettepilot

I believe that connector is typically located in the vacinity or on the RFD. The thing that looks like a 1/8 size propane tank near the fire wall.