Auto A/C question non P-car

[Zeke]

Due to inactivity lately I let my truck sit for maybe 3 weeks w/o starting it. I'm surprised at myself for being so lax. Anyway...

The battery was stone dead as in the radio lost its memory. I'm sure I damaged the battery which is less than a year old. It works so I won't be able to warranty it but I can tell it lost some cranking amps. I have a load tester and it's just barely there under load. I charged the battery slowly over a day and am now using a solar charger for float charge.

I drove the truck the next day and the A/C is dead — no cold air. Checked fuses, compressor clutch and low pressure cut-off switch and all are good. However, the refrigerant charge is next to nothing. There is minimum pressure so no ambient air got in. I have the gauges and vacuum pump if I need to go that route. But for now, I'm going to add some r134a and see how it goes.

Now to the A/C question: is it somehow possible that sitting for 3 weeks has something to do with this other than coincidence? I've had this truck for over 8 years and I've never had a problem with the A/C. It's been ice cold all along. never needed service. I don't get it other than one shouldn't leave a vehicle idle for long periods of time. I though a long period was months, not 3 weeks.

BTW, I can't see the evaporator but the rest of the system is dry. Lord help me if I have to change out the evap.

[Hugh R]

Turn on the A/C if you hear the magnetic clutch engaging and disengaging you are probably low on R-134a, you can get a can from Walmart or autozone. You should puta digital thermometer in the center vent, add a little R-134A at a time, do not invert they can! You can liquid slug the system and hydro lock it. When the temp quits dropping in the vent, stop immediately.

[1990C4S]

I vote coincidence.

[rusnak]

^ he says he has the gauge set and a vacuum pump. When you fill 134a you really need the high and low pressures as well as an ambient temperature chart.

Can you jumper the low pressure cutoff switch to verify that the compressor runs?

[Scott Douglas]

Rule of thumb from the last tech that charged our systems in our cars said to run the A/C at least once a week to keep the seals lubed. I have the same problem of not using the car enough lately. Have to force myself to get it out of the garage and go for a drive.
On the battery situation, I'd check to see what the draw is on it after it's charged up and shut down. I'd think an older vehicle without a bunch of electronics in it could last longer than 3 wks without the battery being charged.
Did you check the amount of electrolyte in the cells by chance?

On the A/C, pull the caps on the fill valves. Any wetness there? That's where my wife's car had a leak. The schrader type valve had a bad seat so it leaked on the low pressure side.

[rfuerst911sc]

Milt you have nothing to lose except a few bucks to go ahead and load a can of refrigerant . You said you tested the compressor clutch but you didn't say if it was engaging . If you are low on refrigerant then obviously you have a leak .

On my wife's Volvo XC90 we lost the refrigerant charge due to a poorly seated Schrader valve . Replaced the valve , pulled a vacuum and charged it up . That was a year ago and still blowing cold . Start slow/easy and go from there . Good luck 👍

[Scott Douglas]

The culprit in our leak. And you never would have known it was leaking until you removed the cap and saw the wetness.

[Bob Kontak]

Originally Posted by rusnak

^ he says he has the gauge set and a vacuum pump. When you fill 134a you really need the high and low pressures as well as an ambient temperature chart.

If your compressor is engaging/cycling then throw a can in. You said it works but not sure what the test was.

If you have a leak that is worthy of a part replacement, your clutch will not engage when running.

Note the new R134 cans have a valve in them and they are not pierced anymore. You will need a new type fill hose.

My bet if a leak is the condenser. Evaporators are such a PITA even for easier to access truck evaporators. Don't allow that be leaking.

Edit: Schrader valves are about 12 bucks to change out.

[asphaltgambler]

No coincidence. Your A/C system has a leak somewhere, likely very minor as it still some left in it. I would charge it with dyed freon. You can by 1lb cans of freon with dye already mixed in. That way when you charge it - you'll be able to spot the leak if it is where you can lay eyes on it. Check to see if the A/C system decal is still attached - so to look for the amount that is needed.

Also there are 'tricks' to charging if you're experienced by introducing more liquid VS gas into the system. More liquid = more condenser saturation = higher ratio of converting ambient temp to vent temp.

[Bob Kontak]

Originally Posted by asphaltgambler

Also there are 'tricks' to charging if you're experienced by introducing more liquid VS gas into the system.

What is liquid VS gas?

[Zeke]

Originally Posted by rusnak

^ he says he has the gauge set and a vacuum pump. When you fill 134a you really need the high and low pressures as well as an ambient temperature chart.

Can you jumper the low pressure cutoff switch to verify that the compressor runs?

Did that and it's fine. Apparently the cut-off switch won't close due to low pressure.

Thanks to the mechanics here.

I do my own household A/C with r410a so I know how to introduce liquid — very slowly. I might buy an in-line expansion fitting to be sure. So far I haven't used one. I'm patient.

The refrigerant in there now has a green dye. Factory? I've heard that sometimes the factory uses that. In fact I have an article bookmarked that says all GM has that since 5/00. Mine is a 2006.

I'll wait 'till tonight to look with a UV light. I have gone over the condenser thorougly.

[asphaltgambler]

Regarding freon there is a certain % of liquid VS gas with every size container that it resides in. I do not know the specific % balance inside any given container- but I do know that if you purposefully introduce more liquid ( to a point) into the system than what normally would occur you can achieve more saturation in the condenser- maki g it more efficient.

A freon containers have the 'tap' or valve at the top with no tube or pickup down to the bottom. So when charging the gas/ liquid mix goes 'up' into the gauge manifold. Since liquid is heavier than gas, it generally 'sits' on the bottom of the container.

So if the system is empty or near empty- I'll turn the can upside down so mostly liquid is entering the gauge manifold. You have to be careful of doing this as too much on the low side can hydra-lock the compressor. So the first can I charge with system 'off' via the high side port. That way you won't harm the compressor.

But doing it this way there will be a point where the system pressure will rise to equal the can pressure. At that point, you'll have to charge via low side with system running to finish.

[asphaltgambler]

So as the system is running, the high pressure generated by the compressor is cooled by the condenser and turns into largely lquid/ gas by the time it hits the expansion valve which meters the mix down to low pressure gas. It's at that point where the cooling takes place. By having a larger % of liquid ( to a point) it become more efficient- not cooler but more efficient in converting high ambient temps and humidity into the cool air coming out of the vents.

[rusnak]

Originally Posted by asphaltgambler

Regarding freon there is a certain % of liquid VS gas with every size container that it resides in. I do not know the specific % balance inside any given container- but I do know that if you purposefully introduce more liquid ( to a point) into the system than what normally would occur you can achieve more saturation in the condenser- maki g it more efficient.

A freon containers have the 'tap' or valve at the top with no tube or pickup down to the bottom. So when charging the gas/ liquid mix goes 'up' into the gauge manifold. Since liquid is heavier than gas, it generally 'sits' on the bottom of the container.

So if the system is empty or near empty- I'll turn the can upside down so mostly liquid is entering the gauge manifold. You have to be careful of doing this as too much on the low side can hydra-lock the compressor. So the first can I charge with system 'off' via the high side port. That way you won't harm the compressor.

But doing it this way there will be a point where the system pressure will rise to equal the can pressure. At that point, you'll have to charge via low side with system running to finish.

This is exactly what I do when I do a charge after a complete evacuation and pull vacuum.

[rusnak]

Originally Posted by Zeke

Did that and it's fine. Apparently the cut-off switch won't close due to low pressure.

Thanks to the mechanics here.

I do my own household A/C with r410a so I know how to introduce liquid — very slowly. I might buy an in-line expansion fitting to be sure. So far I haven't used one. I'm patient.

The refrigerant in there now has a green dye. Factory? I've heard that sometimes the factory uses that. In fact I have an article bookmarked that says all GM has that since 5/00. Mine is a 2006.

I'll wait 'till tonight to look with a UV light. I have gone over the condenser thorougly.

That's why you have to jump the low pressure cutoff switch.

[Baz]

Mr. Milt....

I'm no expert but when my Silverado had a leak issue, it was the o-ring like Scott's pic up above (Post #7).

Worth checking out.

Also - don't forget to add a small can of oil with your Freon, unless yours already has it in it. I think some do. Mine didn't. Here's what I used from Walmart:

[Zeke]

Originally Posted by rusnak

That's why you have to jump the low pressure cutoff switch.

We are going 'round and 'round. What do I have to say to convince you that I took the fooking connector off the dryer and jumped them.

[rusnak]

Lol!

I'm ....think...number....1....10. ....is...it? You can't fooking read my mind?

[Bob Kontak]

Originally Posted by asphaltgambler

Regarding freon there is a certain % of liquid VS gas with every size container that it resides in.

Great googly moogly. I am thinking there is a tangible product called liquid VS gas. Like Liquid Victoria's Secret Gas. Doh! Versus. I always use lower case vs. Sorry to bug you.

I learned of liquid charging the high side with engine off during the AC wars threads several years ago in the tech forum. I did it a few times but I'm never much in a hurry anymore so seldom bother. Plus if the system works well it does not take that much time charging with the tank upright.

[cabmandone]

Originally Posted by Bob Kontak

What is liquid VS gas?

Tip the can upside down and you're charging with liquid. Do so VERY slowly or you can do damage. Right side up you're pulling vapor which is why you have to put the can in warm water to boil off the liquid to increase vapor pressure.

You can liquid "slug" the compressor and hurt the compressor if you charge with liquid into the suction side.