AC Compressor Cycles on and OFF

[Chris Talarico]

My air conditioner is now blowing hot air. The compressor cycles on and off every 5 seconds. Anyone else have this going on? I checked the pressure and it was was to high, so I lowered it and it still happens. I ordered a new cycling switch for it and will try that first. Then I will look at the orifice tube!!!

Help its hot out

 

[Dreman]

Too high? I would guess too low! Are you sure you checked the right end? What pressure did you have?

 

[Chris Talarico]

I checked the low side pressure. it was like 110psi. so I lowered it to 45ish. Could it maybe be an orifice tube?

 

[Dreman]

Did you check it with the system running or not running?

 

[Chris Talarico]

yes system is on max ac. No Cold air and comprssor goes on and off every 5 seconds. Is that normal?

 

[Dreman]

It's not normal. Mine recently went through something similar, but my problem was low refrigerant. Adding more R134a fixed it. If you have decent pressure, it sounds like you may have either a bad low pressure switch or a bad orifice tube, although I haven't looked to see if we even have orifice tubes on our systems. If you have the gauges hooked up, try bypassing the low pressure switch for a few seconds to see if the pressure on the low side drops to a reasonable level. However, since you've let some out, I expect it will go too low now!



If the pressure drops on the low side, you need a new low pressure switch. Which means evacuating the system, changing the switch, pulling a vacuum on the system, and refilling. It's no worse than changing the orifice tube would be, though!

 

[Chris Talarico]

Thanks for the feedback.

I know the low pressure side drops when the compressor kicks on.

Is the low pressure switch the same as the cycling switch.

Thanks in advance

 

[Art G]

If AC is operating properly, it is not normal when compressor cycles off/on every 5 seconds.

Hook an AC manifold gauge on the Low and High pressure lines and start the car with AC set at MAX. If you don't have the manifold gauge, I recommend to take to an AC shop. The low pressure should read between 40 to 50 psi and the high side should be somewhere between 250-300 psi. If you don't have these readings, you need to add R134 freon.

Artstang

 

[Gerald Pierce]

Mine did the same, I added a can (bought the one with the gauge) and it fixed the problem Ice cold now!

 

[EddieS'04]

As dreman said, you need to bypass the low presure switch. With the system cycling your are seeing equalized pressure. Not the true low reading.

 

[Richard L]

rico,

Yes, it sounds like the orfice tube is clogged, but simply replacing it is not the solution. When an orfice tube cloggs up it means something else has failed and the debris has gotten stuck in the orfice tube.



It could be something as simple as ait getting into the system and forming ice which blocks the orfice tube, or it could be that the compressor is failing. Many parts in modern AC systems are teflon coated and when they fail the teflon flakes off and migrates troughtout the system. The system will likely need to be dismantled, and checked for debris and where the debris came from (compressor is the most common problem) The system needs to be cleaned and flushed out, the orfice tube, and Accumulator/dryer replaced along with the failed part, and the system evacuated and recharged with refrigerant, and compressor oil.



Depending upon what part actually failed, you are probably looking at about $500-$700

minimum for repairs.



Often times, the compressor failure will clogg up the evaporator and or condensor cores so bad that they cannot be cleaned out and need to be replaced. The compressor, condensor and evaporator are the main components of the AC system and replacing all of them could easily run $2000 or more.



...Rich

 

[scott degroot]

Normal operating pressures for a typical ac system at 80 degrees ambient is about 20-35 on the low side and about 200 on the high side with the compressor engaged. If the ac comp is cycling about every 5 seconds that is usually an indication that the system is low on refrigerant. What did you use to check the pressures with? If you used a set of manifold gauges I hope you didn't open the valves on the manifold becasue that would have the high side and low side readings trying to show up on both gauges. What does the low side drop to when the compressor cycles. if the pressure on the low side stays above about 22 psi the compressor should run continously.

 

[Martin]

Often times, the compressor failure will clogg up the evaporator and or condensor cores so bad that they cannot be cleaned out and need to be replaced. The compressor, condensor and evaporator are the main components of the AC system and replacing all of them could easily run $2000 or more



This happened to me one time with a Crown Vic.....it ran me just under 3K to have everything replaced.

 

[Richard L]

DesertFox,

I guess my prices are closer to the 1988 prices than the 2008 prices...:lol::lol:



...Rich

 

[Jason Dieterle]

I have a similar problem with the AC cycling. The interesting part is that when the truck is in park, there is no cycling and the low side pressure is reasonable, around 50 psi. When I shift into drive, the cycling starts, and the pressure goes up. I am using the gauge that came with the recharge kit, which goes up to 80 psi, and the needle goes off the scale. Any ideas?