Quick A/C Tip

[NOT A 45]

I see a lot of guys on here with a/c concerns. Obviously most people do not have access to recovery/charging equipment, but a a/c pressure gauge is relatively inexpensive. Here is a quick easy way to see if refrigerant charge is your problem.

With a completely cold car (i.e. sitting in the garage overnight and without starting the engine) connect your pressure gauge to either the high side or low side fitting and test the pressure. The general rule is that on a fully charged system you should read close to ambient air temp. So if your garage is 70 degrees expect to see 70-75 psi on your gauge. If your within a few psi of that, you can pretty much eliminate that as a possible source of your problem and start looking elsewhere.

[romcjr]

Good tip !! Thanks

[silversleeper]

AC is hard for an amateur like myself to get correct.
https://www.camaro5.com/forums/showthread.php?t=559278
has more info.
I'll attach a chart for the camaro from the manual. You can see the general guidance of the low pressure side of the AC should be about the same as outside temperature in DEGREES Celsius (not Fahrenheit).
In my limited experience they are too sensitive to the amount of freon in the system.
The "book" says vacuum it out then add exactly X amount. Ok great I got a vacuum but measuring that exact amount isn't easy, and when that still doesn't work you realize you didn't get every ounce of oil out of the system so that "amount" would overcharge it. Add too much oil and it doesn't cool good, not enough risks compressor damage.
The only way I got it to working is to pay more attention to the high pressure side being correct than the low pressure side. Good luck on AC repairs.

[Ashen 6.2]

Originally Posted by NOT A 45

I see a lot of guys on here with a/c concerns. Obviously most people do not have access to recovery/charging equipment, but a a/c pressure gauge is relatively inexpensive. Here is a quick easy way to see if refrigerant charge is your problem.

With a completely cold car (i.e. sitting in the garage overnight and without starting the engine) connect your pressure gauge to either the high side or low side fitting and test the pressure. The general rule is that on a fully charged system you should read close to ambient air temp. So if your garage is 70 degrees expect to see 70-75 psi on your gauge. If your within a few psi of that, you can pretty much eliminate that as a possible source of your problem and start looking elsewhere.

Great info! Any recommendations on a/c pressure gauges to get? Or stay way from? lol

[gtstorey]

I haven’t had any problems with my gauges from HarborFreight

[Ashen 6.2]

Originally Posted by gtstorey

I haven’t had any problems with my gauges from HarborFreight

Thanks gtstorey!

[Brutale arancia]

Originally Posted by NOT A 45

I see a lot of guys on here with a/c concerns. Obviously most people do not have access to recovery/charging equipment, but a a/c pressure gauge is relatively inexpensive. Here is a quick easy way to see if refrigerant charge is your problem.

With a completely cold car (i.e. sitting in the garage overnight and without starting the engine) connect your pressure gauge to either the high side or low side fitting and test the pressure. The general rule is that on a fully charged system you should read close to ambient air temp. So if your garage is 70 degrees expect to see 70-75 psi on your gauge. If your within a few psi of that, you can pretty much eliminate that as a possible source of your problem and start looking elsewhere.

Your valuable input IS appreciated.

[NOT A 45]

Originally Posted by gtstorey

I haven’t had any problems with my gauges from HarborFreight

Yes I agree, for most people the Harbor Freight gauges are fine, and are inexpensive. A lot of Harbor Freight stuff is actually decent.

[NOT A 45]

Originally Posted by silversleeper

AC is hard for an amateur like myself to get correct.
https://www.camaro5.com/forums/showthread.php?t=559278
has more info.
I'll attach a chart for the camaro from the manual. You can see the general guidance of the low pressure side of the AC should be about the same as outside temperature in DEGREES Celsius (not Fahrenheit).
In my limited experience they are too sensitive to the amount of freon in the system.
The "book" says vacuum it out then add exactly X amount. Ok great I got a vacuum but measuring that exact amount isn't easy, and when that still doesn't work you realize you didn't get every ounce of oil out of the system so that "amount" would overcharge it. Add too much oil and it doesn't cool good, not enough risks compressor damage.
The only way I got it to working is to pay more attention to the high pressure side being correct than the low pressure side. Good luck on AC repairs.

Those are working pressures. The test I'm referring to is a static pressure test....engine off and cold. It's just a simple easy test to see if your a/c problem is because it's low on charge without removing the refrigerant.

[silversleeper]

Originally Posted by NOT A 45

Those are working pressures. The test I'm referring to is a static pressure test....engine off and cold. It's just a simple easy test to see if your a/c problem is because it's low on charge without removing the refrigerant.

Ah, thanks for making that clear . I've always been told to check it with it running which obviously makes the low side lower and high side much higher. I could see where a quick check without it running could be useful.
The built in refill can gauge with proper pressure similar to a fire extinguisher is way off going for the blue/green if we didn't know it's for running pressures, but would still work if we use the rule of thumb for static pressure and ignore the blue/green markings.
Edit: I got my guages off amazon, similar to harbor freight set. I needed the high and low. The trick is to know when to turn off the valves on the manifold on the gauges so you don't back bleed the freon, or try to push back the high to the low side.

[camguynj]

Originally Posted by NOT A 45

I see a lot of guys on here with a/c concerns. Obviously most people do not have access to recovery/charging equipment, but a a/c pressure gauge is relatively inexpensive. Here is a quick easy way to see if refrigerant charge is your problem.

With a completely cold car (i.e. sitting in the garage overnight and without starting the engine) connect your pressure gauge to either the high side or low side fitting and test the pressure. The general rule is that on a fully charged system you should read close to ambient air temp. So if your garage is 70 degrees expect to see 70-75 psi on your gauge. If your within a few psi of that, you can pretty much eliminate that as a possible source of your problem and start looking elsewhere.

What would be the simplest stand-alone single gauge set up you could use without having to buy a complete manifold guage set? Thanks

[NOT A 45]

Originally Posted by camguynj

What would be the simplest stand-alone single gauge set up you could use without having to buy a complete manifold guage set? Thanks

I don't know of any, but a set of gauges from harbor freight are inexpensive. They have a nice set on clearance for $49

[silversleeper]

Please excuse me if this post is mostly an echo of what 45 said. +1 type comment if you will.

Some things you realize later and say to yourself, I wished I would have just got this earlier. That's the hi and lo and refill gauge set.
If you're just going to attempt it once and not very interested in repairs the walmart gauge on the refill can "kit" or this can get you going. I have had a few of those super cheap on-can gauges and one of these cheap hose-gauge be innacurate/broken. You don't want that trying to refill, the pressures are touchy and need to be correct.

I wished I got this type set sooner because it's worth it if you're trying to diagnose a problem and fill more accurately.

https://www.harborfreight.com/ac-r13...60806.html?utm

[Badbubba]

[QUOTE=silversleeper;11182822]AC is hard for an amateur like myself to get correct.
https://www.camaro5.com/forums/showthread.php?t=559278
has more info.
I'll attach a chart for the camaro from the manual. You can see the general guidance of the low pressure side of the AC should be about the same as outside temperature in DEGREES Celsius (not Fahrenheit).
In my limited experience they are too sensitive to the amount of freon in the system.
The "book" says vacuum it out then add exactly X amount. Ok great I got a vacuum but measuring that exact amount isn't easy, and when that still doesn't work you realize you didn't get every ounce of oil out of the system so that "amount" would overcharge it. Add too much oil and it doesn't cool good, not enough risks compressor damage.
The only way I got it to working is to pay more attention to the high pressure side being correct than the low pressure side. Good luck on AC repairs.
[SIZE=2]

Recovering and then vacuuming down a system does not remove the oil. It will remove the water from the oil by boiling it off due to the low pressure. As well as evacuate it. Oil becomes an issues when one tops off their system with cans that contain stop leak. Too much gets added to the system. Do not add oil unless one knows oil was lost or is a new system. Top off cans often contain oil or stop leak and oil combined. Too much oil will affect cooling performance or possibly damage certain compressors.
You will lose oil due to leaks. And an easy way to find a leak is to look for a "greasy" area. Oil will collect dirt, appears greasy. The filter/dryer should be replaced when a system is opened up, although most people don't. Yeah, not much of a window for charging most of the modern systems. Quality scale needed.