a/c clutch ?'s

[p24-1953]

with the help of ruth1932 i have charged my a/c and went on my maiden voyage..... its was a balmy 85 and my wife got cold.... success....

now having said all of that i do have one question. the first time i turn the a/c on after the car has sat for a while you can hear the compressor clutch cycle on and off for 30 secs or so before is stays engaged. after that it will cycle on and off with no problems , what could be causing this? is it normal?

[p24-1953]

well a little update to day ..it is closer to 90 and the clutch cycling lasted for a min or so. I am concerened that i will damage the clutch if i let it go, and apperantly hot rod air is now out of business so i cant ask them. what could cause the clutch to cycle on and off? i am getting 13.4 volts, and it happens even if you bypass the low pressure saftey switch.

[Plymouthy Adams]

low charge for one...when charging your system, how much freon did you install, what was the high side and the low side reading..do you have a sight glass...remember R134 is approximately 85% of R12 charge weight if charging by volume on a conversion..as you stated additional length hoses were involved...as it is cyclying...I take it you have a low pressure safety cut off swtich..if that is not right, is the evaporator thermostat inserted properly in the evaporator..and on the expansion valve is the sensor coil ofor it properly affixed to the inlet and wrapped with expansion tape?

[p24-1953]

tim, i for got to wrap the black take on the expansion valve. would that do it?

okay i had sketched up a diagrahm of the electrical system but due to scanner error i can not post it. the electrical has a 12v input going into a 3 way switch that controls the fan speed. from the back of this a blue wire goes to a thermostat. then the blue wire goes to a binary saftey switch on the drier, then on to the compressor.

heres the tests i did:

1: put a jumper on the binary saftey switch on the drier. i still got the clicking clutch.

2: checked voltage at the clutch 13.4 volts ? amps(i dont know how to test amps)

3: checks coil resistance 4.2 ohms - Okay

4: place jumper to remove thermosat... Still got the clicking

5: placed guages on high and low with car off... My guages have a outer ring of number labled R134a and a inner ring labled psi both of mine read 25(r134a) or 85 psi.

6: with the car running the guages read low side -7(r134a) or 19 psi. High side reads 75(r134a) or 325psi

what do i need to check now? it does not look like the clutch is slipping it looks like it is just switching on and off. would a low amp situation cause this. A Sanden tech emailed me that i need to check that but i dont know how.

[Harvey Tank]

in my experance about 80% of refrigeration problems are electrical, the remaning 20% are found to be with in the refrigeration circuit. why don't you do the process of elemination. you have 2 wiitches, the thermostat and the low pressure switch. is that right? what I would do is by pass everything. then with your guages hooked up to the system, take a jumper wire with an in line fuse say 5 or 10 amp. and go right to the compressor. not knowing your electrical set up. pos. ground or neg. ground. which ever one you have come right from the battery bypass everything. of course with a fuse in the jumper. when the compressor starts. observe your pressurs on the guages. if the clutch stays energized. then you know it is eather the thermostat or low pressure switch. if you find that is the low pressure switch, chanches are the system is under charged. PM me and we will go over it again. if you find it is the thermostat it could be in the wrong loation or the thermostat could be bad. like Tim said the thermostat sensor has to be in the right location. sometime the sensor in buried in to the evaporator and somtime in the air stream. watch your discharge pressure if if goes out of site remove the jumper.

[p24-1953]

found the problem... as a last ditch effort i replaced the factory supplied cuircut breaker, and low and behold alll of the problems i was having went away. it must have beeen defective and restricted the amps a little to much so that the clutch was not getting the full 7 amps required to engage the clutch intially.

[Plymouthy Adams]

loss of voltage will keep a system in-op..you made no mention of loss of evaporator fan, this would have been the tip off to your problem being voltage related as the power feed is from battery, through the circuit breaker, through the off/on fan switch, to the evaporator thermostat, on to the binary switch and through the clutch coil to ground thus completing the circuit......

glad you got it going..

[p24-1953]

the evap fan kept working and the clutch would eventually engage, but when i replaced that part everything works just fine. strange, but im okay with that becasue it works.

[Harvey Tank]

glad you found the problem! can you post some photos? I would like to see the A/C instulation.