A/C compressor cycling on and off

[crawdad]

Hey guys, the A/C compressor in my truck keeps cycling on and off, and this is when its in the "off" position! Any ideas what might be causing this? Thanks for your help.

[Slonaker]

Does it cycle on and off when the A/C is turned on? If so, you are low on refrigerant.

Here is the part where I make a wild guess... As far as it doing it in the OFF position, my A/C runs in every position except OFF and HEAT. I think the dash controls are bad on mine, but I have not had a chance to replace them. Maybe you have two problems, low refrigerant and bad dash controls that don't turn your A/C off?

Slonaker

[crawdad]

Yes, it will cycle on and off with the A/C on too. I have to keep it on vent for it to shut off. I'm going to have the system leak tested and recharged next week. Is the dash control a hard item to replace?

[Oldtruckfanatic]

Most ac systems will cause the compressor to cycle on and off even if the ac isn't on when the charge gets low.

[Slonaker]

Originally Posted by crawdad

Yes, it will cycle on and off with the A/C on too. I have to keep it on vent for it to shut off. I'm going to have the system leak tested and recharged next week. Is the dash control a hard item to replace?

I don't know from personal experience because my new one is still sitting in the box on a shelf above my workbench. I know that 86swb did his, and I think he said it was not too difficult. You might PM him for details.

BTW, I bought the part from an auto parts store that sells AC Delco parts. I think it was about $50. Getting stuff through the parts store is usually a lot cheaper than the dealer, though I did not compare the prices this time.

Slonaker

[piecesparts]

The hardest thing about changing out the dash control is getting the dash apart to be able to pull it out far enough to remove the vacuum fittings and electrical connections. After that everything is easy.

[bodydropped]

mine was low and it cycled until it broke the face off i put a new face on it and went to town again and charged it up

[cliffsta]

Originally Posted by piecesparts

The hardest thing about changing out the dash control is getting the dash apart to be able to pull it out far enough to remove the vacuum fittings and electrical connections. After that everything is easy.

I concur... if your dash bezel is old and brittle, getting it off and in one piece is a bia. We changed the fan speed switch back in August and we could barely pull the thing a few inches before it started cracking. Ended up using dentist tools to change the switch.

I'd suggest checking the rest of the system IF your dash bezel is in poor shape, or else you might end up dropping money on a HVAC control AND a dash bezel.

Good luck

[crawdad]

Ok, thanks for the help everybody. I'll let you know how it goes.

[mhicks]

I have a shop manual for a '73 and it says that the compressor should be on in all positions except off, vent and heat. The low pressure switch is in series with the compressor so if it is low on freon it will not come on or it will cycle.