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Ok, I have a 98 Town Car and the compressor turns on for 5-10 seconds then off. On then off etc…..
The air conditioner is not cold because of that. To keep the compressor on I removed the relay and jumped the terminals to turn it on. The low side was below 15 psi. I hooked up the 18oz can of Arctic Chill and put the whole can in.
After disconnecting the can, but keeping the gauge on I put the relay back in and watched the gauge go up and down.
So…
compressor on=gauge goes down to 25 psi THEN compressor turns off
pressure rises to 45/46 THEN compressor kicks ON And the pressure begins to go DOWN
pressure goes down to 25 AND compressor turns OFF.If I bypass the relay, the compressor runs and stays on.
Why is the pressure level fluctuating?? Is it supposed to fluctuate like that??
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That car has a cycling compressor clutch switch (CCOT) type system. It shuts the compressor off at approximately 22 to 26 psi and turns it on again a around 44 psi. The system contains an orfice tube that meters the refrigerant into the evaporator to allow cooling to take place. If the system is low on charge the process takes place too quickly in regards to pressures so cooling does not take place and the compressor clutch cycles rapidly.
That system holds over 4 lbs if memory serves me so you will need to add more to make it work as intended.
I would have it professionally checked out (leak checked) so the job is done correctly with the correct refrigerant.
:woohoo: Wow that makes me feel way better!! I had no idea. Is that all town cars and crown vics???
Anywho, so what you’re saying is that I probably don’t have enough refrigerant in the system?? If so, how and why would the gauge be reading full??
Also Bill, If the car doesn’t have the required amount of refrigerant/oil mix wouldn’t it show a different pressure reading on the low side gauge??
p.s. I only have the low side gauge 🙁
With the correct amount of refrigerant you will find the pressure will drop at a much slower rate and raise at a slower rate when the compressor cuts out. Also when the car has sat, like over night you should find the pressure very close to the ambient temperature with the engine shut off (at least with 134a)
Not sure about Arctic Chill.
[quote=”wysetech” post=60165]Ummm…….Which gauge?[/quote]
The gauge that reads the low pressure port. That’s the only one I have.
[quote=”wysetech” post=60166]With the correct amount of refrigerant you will find the pressure will drop at a much slower rate and raise at a slower rate when the compressor cuts out. Also when the car has sat, like over night you should find the pressure very close to the ambient temperature with the engine shut off (at least with 134a)
Not sure about Arctic Chill.[/quote]
So I may have the correct pressure reading, but not the correct amount of refrigerant??? A/c is mind boggling…..I’d think if there wasn’t enough then the pressure wouldn’t be there (kind of like a tire with very little air). Does that make sense???
Or is because AC turns from gas to liquid????
If you had a high pressure gauge you would probably find it reading low and maybe the whole deal would make more sense.There is a temperature/pressure relationship. High side pressure is usually between 150 and 250 psi
There could be other problems with the system but from what you describe it’s a classic Ford low charge.
ok, so I borrowed a manifold gauge.
The the relay jumped so that the compressor stays on and an ambient temp of 68 F
the low side was at 22 and high side of approx. 180
With the relay plugged in, the compressor began cycling again off/on. Turns on at 44 psi and turns off at 20-21 psi. And it isn’t slow. It’s a decently fast cycle.
So, any indication of these numbers??
see if this chart helps.
http://www.idqusa.com/faqs.php?faq=74&faq_id=74&category_id=18
If the system blows cold you’re likely in the ball park. The high side pressure is a bit high but it’s possible that the fan clutch is weak or it hadn’t hooked up yet. There could also be air in the system which could effect the whole system as well as the pressures.
If it holds a charge long enough the compressor will run at longer intervals when the weather is hot.
PS..Not sure if you knew but the compressor cycles to prevent the condensation on the evaporater from freezing.
[quote=”wysetech” post=60322]If the system blows cold you’re likely in the ball park. The high side pressure is a bit high but it’s possible that the fan clutch is weak or it hadn’t hooked up yet. There could also be air in the system which could effect the whole system as well as the pressures.
If it holds a charge long enough the compressor will run at longer intervals when the weather is hot.
PS..Not sure if you knew but the compressor cycles to prevent the condensation on the evaporater from freezing.[/quote]
Yeah, I think I’m getting close as well. Maybe 4oz more, taking into account that about 2oz is left in the hose in the back of my mind. But I might leave it as is cause from what I’ve read it’s better to be under pressure (low side) than over do it.
Yes I also saw where you posted that the compressor does cycle. I was able to pull an alldata as far as how long it is supposed to cycle for and it’s definately on the lower side of the spectrum, but the alldata doesn’t say what to do IF you are too low or high. I guess that’s when experience kicks in…..which I have very minimal as far as A/C.
Do you think a little more refrigerant will increase the low side AND bring the high side down or would both go up?? (I think both go up but I’d still rather ask)
If you add too much refrigerant the high and low side will increase but the compressor may have a stroke. Ideally the low side pressure is just about where it needs to be. I have seen high side pressures reach 400 psi from an overcharge.
[quote=”wysetech” post=60339]If you add too much refrigerant the high and low side will increase but the compressor may have a stroke. Ideally the low side pressure is just about where it needs to be. I have seen high side pressures reach 400 psi from an overcharge.[/quote]
Well hot damn!!!! Thanks for all the help. Hopefully it stays chilly
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