Cryostat no longer cools

Hook up a set of gauges and see what the pressures are. If while running the low side drops to 15-20 psi and the compressor cycles off then more that likely it is low on freon and needs a recharge.

The problem is probably the starter asm. on the compressor, though it could be signs that the compressor is failing. An amp draw test would be a good place to start

Have you watched the compressor in action? The compressor is driven by the fanbelt which turns a pulley on the compressor shaft, but there's an electric clutch that disengages the pulley from the friction plate attached to the compressor shaft. You should hear a click when the clutch engages and disengages. Do you hear that? Can you see the friction plate turning with the pulley or does it stay in one position while the pulley turns? If if works for a bit then stops turning, you may have a damaged friction plate such that it doesn't engage with the pulley. Take your car to an auto A/C specialist and let them examine it. It's also possible that the relay that sends 12 volts to the clutch is intermittent and needs to be replaced.

1. Check if air blows with the fan setting turned to high.
2. Check that the radiator cooling fan engages when the A/C button is pressed.
3. Locate the compressor.
4. Turn on the A/C.
5. Check if the compressor's clutch has been engaged.
6. If the clutch engages, the fault is elsewhere.
7. If the clutch does not engage, check for power to the clutch.

These steps might help find the problem.

Check the Capacitor

the motor is working too hard or the power source is not adequate or you are using a extension cord never use a extension cord for a air compressor you will destroy the motor over time use longer hose and plug it in to the outlet directly

Hello
You need to complete the 24 volt circut from the themostat to the transformer to get the contactor to pull in.

Check for voltage at the transformer,should be 120 v in 24 volts out.Also there may be a small reset button on the transformer.

no there is reset,but,the ptc overload relay plugged into the compressor is bad,purchase a new replacement ptc overload relay and plug in into the compressor and it will again cool properly

Hi and welcome to FixYa. I am Kelly,

There is no reset button. There is a thermal overload on the compressor called a KliXon and that is what should be cycling about every 5 - 8 minutes if the compresor did not start.

When there is a temporary loss of power 10 minutes or less there is a good possibility that the internal coolant pressures are way to high for the compressor to start. Unplug the unit for 15 - 20 minutes and plug it back in FIRST. (longer is better) This will give the coolant system time to equalize so the compressor can start. If after trying the unplug / wait / re-pulg routine it still does ot start or cool just repsond here and I will gladly help you.

Thanks for choosing FixYa,

Kelly

Hi,
There may be a manual reset high limit... look for a red button on a round part hooked to the small copper line and push it in hard...
Also the compressor may have kicked the overload and needs a few hours to cool and it reset, that is interanl insdie the compressor.
Contactor may also have went bad...

Here is a tip about troubleshooting your air conditioner...
There are many things that can cause your air conditioner not to cool...

Air Conditioner Trouble - Review the Possibilities

heatman101