99 A/C cutting off. Full charge 134a.
06-20-2017, 03:40 PM
#16
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Year: 1994
Model: Grand Cherokee
Engine: v8
Thanks Dave, that's kinda what I am suspecting. The sucky thing is that the orifice is "captured", so I cant just replace it. I actually have 10 of them on hand due to an accidental order.
Fortunately, the two parts you mentioned are only $65 total and about $15 worth of gas. I'm just really cheap and hate throwing parts at something until it's fixed.
Fortunately, the two parts you mentioned are only $65 total and about $15 worth of gas. I'm just really cheap and hate throwing parts at something until it's fixed.
06-21-2017, 11:12 AM
#17
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Year: 1998
Model: Grand Cherokee
Engine: I6 - 4.0
The low pressure switch shouldn't open until there is a danger of freezing the inside coil. I don't have a P/T chart in front of me but I would project that pressure to be below 20 lbs. Normal operating suction pressure would be about 30 lbs. or so - so If the LP switch is opening at 60 lbs. It would be defective.
PHM
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PHM
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I am just measuring on the low side right now. Presumably they are equal when the system is static (it's 100psi or so static).
When the compressor starts, the low side pressure drops down to 60-70psi and then the compressor drops out(eta) within seconds. The pressure then rises back to approx. 100psi for a few seconds, then the compressor starts again. Rinse/repeat.
When the compressor starts, the low side pressure drops down to 60-70psi and then the compressor drops out(eta) within seconds. The pressure then rises back to approx. 100psi for a few seconds, then the compressor starts again. Rinse/repeat.
06-21-2017, 11:19 AM
#18
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Year: 1998
Model: Grand Cherokee
Engine: I6 - 4.0
If you have the LP switch bypassed - I think we can eliminate that as the cause of the short cycling. <g>
I'm only a refrigerant genius - not an auto A/C guy - so now we need someone who is to tell us:
What else interrupts the power to the compressor clutch on these vehicles? If it's not the LP switch - what else can it be?
Wait a minute! Is there a high pressure cutout? With only a LP gauge attached we have no idea what the head pressure is - is there a HP switch as well?
PHM
--------
atch
I'm only a refrigerant genius - not an auto A/C guy - so now we need someone who is to tell us:
What else interrupts the power to the compressor clutch on these vehicles? If it's not the LP switch - what else can it be?
Wait a minute! Is there a high pressure cutout? With only a LP gauge attached we have no idea what the head pressure is - is there a HP switch as well?
PHM
--------
atch
I'm going to put the "real" gauges on it this weekend when she is here, but I think that there is more to this issue than low gas. The compressor behavior is different than it or any other car I have serviced, when it is "low". It literally runs for two seconds and drops out.
also, It shouldn't have cut out when the low pressure switch was bypassed, no?
also, It shouldn't have cut out when the low pressure switch was bypassed, no?
06-21-2017, 02:04 PM
#19
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If you have the LP switch bypassed - I think we can eliminate that as the cause of the short cycling. <g>
I'm only a refrigerant genius - not an auto A/C guy - so now we need someone who is to tell us:
What else interrupts the power to the compressor clutch on these vehicles? If it's not the LP switch - what else can it be?
Wait a minute! Is there a high pressure cutout? With only a LP gauge attached we have no idea what the head pressure is - is there a HP switch as well?
PHM
--------
atch
I'm only a refrigerant genius - not an auto A/C guy - so now we need someone who is to tell us:
What else interrupts the power to the compressor clutch on these vehicles? If it's not the LP switch - what else can it be?
Wait a minute! Is there a high pressure cutout? With only a LP gauge attached we have no idea what the head pressure is - is there a HP switch as well?
PHM
--------
atch
07-08-2017, 10:33 PM
#21
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Year: 1994
Model: Grand Cherokee
Engine: v8
Sorry for the late update.
The dumb thing started working again, but I checked it anyhow with my gauge set.
The pressures were in the normal range of 240 ish and 40 low. I don't remember exactly, as the system was working properly so I really didn't care.
FWIW, the a/c gauge set was reading 10 psi different than the cheapo fill can gauge. I presume that the pro grade is the accurate reading.
The dumb thing started working again, but I checked it anyhow with my gauge set.
The pressures were in the normal range of 240 ish and 40 low. I don't remember exactly, as the system was working properly so I really didn't care.
FWIW, the a/c gauge set was reading 10 psi different than the cheapo fill can gauge. I presume that the pro grade is the accurate reading.
07-15-2017, 05:13 PM
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Sorry for the late update.
The dumb thing started working again, but I checked it anyhow with my gauge set.
The pressures were in the normal range of 240 ish and 40 low. I don't remember exactly, as the system was working properly so I really didn't care.
FWIW, the a/c gauge set was reading 10 psi different than the cheapo fill can gauge. I presume that the pro grade is the accurate reading.
The dumb thing started working again, but I checked it anyhow with my gauge set.
The pressures were in the normal range of 240 ish and 40 low. I don't remember exactly, as the system was working properly so I really didn't care.
FWIW, the a/c gauge set was reading 10 psi different than the cheapo fill can gauge. I presume that the pro grade is the accurate reading.
