A/C Compressor Rapid Cycle

[AntMan]

My compressor (converted to R134) will cycle on for about 2 seconds and off for 10 seconds then repeat. Freon, just added.
Any ideas?

 

[TLIMITED]

Bad low pressure cycling switch on drier.

 

[AntMan]

Great, if I remember correctly you can jump or bypass the low pressure switch (troubleshooting purposes) and the compressor will stay on.

 

[pacecarta]

is your blower fan on high ?

 

[TurboDave]

Bad low pressure cycling switch on drier.

They're adjustable.

 

[AntMan]

Yes, ran on High speed......symptom occurs at any fan speed.

 

[AntMan]

How do you adjust?

 

[pacecarta]

first make sure the sytem is properly charged , a low charge and the compressor will not stay engaged , you could be overcharged and hitting the overpressure limiter in the compressor

the adjustment is on the clutch cycle switch on the dryer , for r12 it may turn off at 24-28psi , for r134 conversions you could have the switch run lower
you have to remove the rubber electrical plug and theres a screw inbetween the terminals but you really need to have a gauge connected and know what your low side cycles down to ,

be aware that 134 should be filled to around 75-80% of what the r12 capicity was.
originally was 3.25 pounds R12, with r134 thats about 3.5 12 oz cans and the retrokits dont include enough for us

 

[Raeban]

R134a runs at a higher pressure than R12 so you may want to set the pressure cycling switch to a higher pressure. Here is a chart that I have used in the past to get it dialed in. It gives a pretty good comparison between the two refrigerant types as well.