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A/C compressor and electric fan are running?
- Thread starter LunchBox
- Start date
Mudderoy
NAXJA Forum User
- Location
- Katy, Texas
It's cold outside so the AC doesn't need to stay on to cool.
Low R134(?) needs a charge.
Low R134(?) needs a charge.
Steve_Moore
NAXJA Forum User
- Location
- Missouri
Doesn't matter if it's cold or not, The A/C will be on no matter what temp if you have the defroster on. It's a pump to take the humidity out of the air.
Mudderoy
NAXJA Forum User
- Location
- Katy, Texas
Well that sucks. Mine goes on and off when it is cold out.
Mudderoy
NAXJA Forum User
- Location
- Katy, Texas
I bet your R134 is low.
Could be. I will have a leak test done this week.
tbburg
NAXJA Forum User
- Location
- Scottsdale AZ
When the system is on "AC" or "defrost", the compressor will cycle off any time it gets a high or low pressure reading. this can happen a couple ways.
If your system is low on refrigerant: The compressor cycles "on", the aux, fan kicks on, and the pressure starts to drop on the low pressure side of the system. As more refrigerant is compressed into liquid, the vapor pressure drops to the point where the low pressure switch shuts the compressor off, and the aux fan also shuts down. With the compressor off, the high and low side system pressures will equalize, tripping the low pressure switch and the compressor comes back on.
With a normal refrig. charge:
On AC, with the fan on low setting, there isn't enough air flow/heat exchange to vaporize the refrigerant in the evaporator coil. The excess liquid in the system causes a vapor pressure drop(same as a low charge) and the compressor cycles off.
On defrost, the outside air temp may not be high enough to vaporize the refrigerant even on medium or high fan settings, and the system will again cycle off.
If your system is low on refrigerant: The compressor cycles "on", the aux, fan kicks on, and the pressure starts to drop on the low pressure side of the system. As more refrigerant is compressed into liquid, the vapor pressure drops to the point where the low pressure switch shuts the compressor off, and the aux fan also shuts down. With the compressor off, the high and low side system pressures will equalize, tripping the low pressure switch and the compressor comes back on.
With a normal refrig. charge:
On AC, with the fan on low setting, there isn't enough air flow/heat exchange to vaporize the refrigerant in the evaporator coil. The excess liquid in the system causes a vapor pressure drop(same as a low charge) and the compressor cycles off.
On defrost, the outside air temp may not be high enough to vaporize the refrigerant even on medium or high fan settings, and the system will again cycle off.
Steve_Moore
NAXJA Forum User
- Location
- Missouri
That seems a like too short a cycle. If your defroster is on it will cycle, but in the ballpark of every 30-40 seconds depending.
hubs97xj
NAXJA Forum User
- Location
- Fort Wayne, IN
That sounds normal to me. If you set the heater control to bilevel or defrost, the compressor runs for short periods- it's to remove moisture from the air, which is how your defroster clears the interior glass.
Now, if the compressor is running when the controls are actually set to heat, then you've got a problem.
Now, if the compressor is running when the controls are actually set to heat, then you've got a problem.
kennzz05
basic dumbass
- Location
- palm coast fl.
id also add that extremely low ambiant temp will prevent the high side from making hardly any pressure which in turn keep the low side from building pressure much above the cutoff point around 25psig i think so you will get constant cycleing due to the lack of load on the system especially when driving and moving air across the cond. coil,eventually when outdoor temp drops low enough there wont even be enough low side pressure to bring the compressor on at all unless you sit still for awhile and everything warms up under the hood enough to defeat the low pressure setting:wave1:
