A/C compressor cycle timing, post service

[MOSHO92]

Hello all,

After 14 years of problem free service my A/C gradually lost some of its cooling power. It was cool, but not cold like it used to be. I took it to a service center to have them look at it and they claimed that, being old, it had probably taken on some moisture and lost some refrigerant.

They vacuumed out the system and then added 3lbs of R-12 (wow..$). Anyhow, the system blows ice cold now, like it did years ago but I noticed something different.

The A/C clutch used to cycle on and off... about 8 times / minute, with the A/C on. Now, when in use, the compressor stays on the whole time.

Is this a sign of over/under charging? Something worse? I'll be honest and tell you that I saved some money going to a hole in the wall shop, but they seemed to know what they were doing.

Thanks!

 

[ShiftyShoMTX]

Compresser cycling is a sign of low refridgerent pressure. So its a good thing its not doing it anmore.

 

[projectSHO89]

Actually, on a correctly charged system, compressor cycling may be normal or it may be completely normal for it to cycle rarely or not at all.

It all depends on how much heat is being transferred and what the ambient conditions happen to be at the time.

In warm weather with the interior fan operating at a higher speed, it's quite normal for the compressor to say on constantly.

If cooler (relatively) conditions prevail and the interior fan is not moving much air through the evaporator, it is quite normal for the clutch to cycle several times per minute.

All that means your system is likely working just fine.

Compressor SHORT-cycling is indeed a symptom of low refrigerant charge.

Steve

 

[MOSHO92]

Thanks!

 

[Sho-N-Go]

3 lbs is too much charge for a Taurus. Also if it is low it had to go somewhere Freon does not just evaporate. Did they add dye for you to drive for a week or so then bring back?

 

[MOSHO92]

Do you happen to know what the correct psi for the SHO is? Could I simply connect a pressure gauge to the schrader valve and check? Also, they didnt add any dye, but is it possible to add the autozone dye with the system fully charged?

 

[projectSHO89]

You have to have a set of guages and the chart from the service manual that takes ambient temp into consideration.

Chances are, they didn't actually put 3 pounds of R12 into your system, but they did charge you for it anyway.

The dye that AutoZone sells is probably set up for dispensing into an R134a system (differenct connectors). You'll be hard-pressed to find an easy-to-inject dye for an R12 system.

I wouldn't worry about it for now, just enjoy the cool air.

Steve