Compressor has no power

[sean9721]

LAst night i took my truck to where my dad works to have the A/C tested. I got new freon and everything. But the compressor clutch still kicks on and off. We narrowed it down to the compressor not getting power. When you hook the compressor up to the battery it works fine. Does anybody have a wiring diagram for the A/C components?

 

[4x4junkie]

It cycling on/off means the compressor clutch is infact getting plenty of power. The problem is elsewhere (most likely improper freon charge).

Did you hook up a proper set of gauges to it to check the freon level? Also, was the ambient air temp warm enough when you checked?

 

[sean9721]

My dad works on ambulances. They have some machine that you can hook up to the A/C system. I got new freon and everything. The air is colder then it used to be. Its just that the clutch turns on and off. And we got a test light and tested the wires going to the compressor but none of them showed power. There is a purple wire that goes to it, but we have no idea where it comes from.

 

[Earl43P]

Compressor clutch SHOULD cycle on and off in normal operation.

What is the ambient temperature at your location?
You can't expect the air conditioner to work much when it's cold outside.

If they had a proper set of guages connected, they should have seen low and high side pressures, adjusted the refrigerant level accordingly and called it good.

It doesn't sound like you have a problem.

 

[shadetree]

Yes, and if it is cycling on and off, it is getting power. If whom ever is adding the refrigerant is qualified, they should know this.shady

 

[sean9721]

Compressor clutch SHOULD cycle on and off in normal operation.

What is the ambient temperature at your location?
You can't expect the air conditioner to work much when it's cold outside.

If they had a proper set of guages connected, they should have seen low and high side pressures, adjusted the refrigerant level accordingly and called it good.

It doesn't sound like you have a problem.

The machine did have high/low gauges. Whenever it gets warm again ill test it. But when the compressor was hooked up to the battery, the air was colder than when it wasnt connected to the battery.

 

[4x4junkie]

It's supposed to cycle so the evaporator coil doesn't frost up due to too-low suction pressure.
Have a place that's qualified look at your system and verify if you have a problem with it or not.

 

[sean9721]

It's supposed to cycle so the evaporator coil doesn't frost up due to too-low suction pressure.
Have a place that's qualified look at your system and verify if you have a problem with it or not.

It clicks on and off repeatedly. I dont think thats normal. I can take a video of it if you need me to.

 

[Earl43P]

Then it might not be properly serviced. Or, it's cold outside.
It's probably slightly low on refrigerant.
Or, it has a bad cycling switch, also called a low pressure switch, usually located on the filter dryer. Depends on what the gages say.

Any COMPETENT AC Tech would recognize a low side suction condition and correct it, either by clearing the blockage in the orifice tube or adding refrigerant. Depends on the gage readings.

High side very high with low side going into suction and tripping the cycling switch means a blockage to me. High side going not very high and low side tripping the cycling switch means add refrigerant. Tain't rocket science. What did the gages say?

You do have to consider how cold it is outside. Wait for a 70+ degree day and see if it stays on for longer cycles. If not, it is PROBABLY slightly low on refrigerant.

We don't need a video, thanks. Gage readings would be nice, along with outside air temperature. When the compresser clutch is engaged, what are the high and low pressure readings at the moment when the clutch DISENGAGES? That'll tell the tale...

 

[Bob Ayers]

Then it might not be properly serviced. Or, it's cold outside.
It's probably slightly low on refrigerant.
Or, it has a bad cycling switch, also called a low pressure switch, usually located on the filter dryer. Depends on what the gages say.

Any COMPETENT AC Tech would recognize a low side suction condition and correct it, either by clearing the blockage in the orifice tube or adding refrigerant. Depends on the gage readings.

High side very high with low side going into suction and tripping the cycling switch means a blockage to me. High side going not very high and low side tripping the cycling switch means add refrigerant. Tain't rocket science. What did the gages say?

You do have to consider how cold it is outside. Wait for a 70+ degree day and see if it stays on for longer cycles. If not, it is PROBABLY slightly low on refrigerant.

We don't need a video, thanks. Gage readings would be nice, along with outside air temperature. When the compresser clutch is engaged, what are the high and low pressure readings at the moment when the clutch DISENGAGES? That'll tell the tale...

Actually a blockage will not cause the head pressure to go that high. Think about it, if the suction side goes into a vacuum, then it won't be adding anything to the high side to compress.....