A/C diagnoses

Divergent Lightning

Divergent Lightning

woah
My A/C has been on the fritz for a little while now. I turn it on and sit there for about 10 minutes with hot air that rivals the heater in my face. It only gets hotter as I slide the temp towards the red. Is there a way to diagnose what needs to be fixed? I really don't want to put much time or money in to it because I don't really use it that often at all. Only when it is really hot...
 
Zewerr

Zewerr

ToeJam is a Poindexter
Re: A/C diagnoses

My guess is you have a leak. Does the compressor clutch engauge? A lot of times you can do a visual inspection of the A/C system and try to find signs of refrigerant oil which signifies a leak. But most of the time to find a leak, you need to recharge the system and use a A/C leak detector or a blacklight with dye in the oil. Don't forget that it might be a good idea to eventually do an R-134a conversion to keep refrigerant costs down. And sometimes you can tell if your evaporator is leaking if you get a refrigerant oil smell (if you know what that smells like) out of your vents.
 
blk00z28

blk00z28

Forced to by choice
Re: A/C diagnoses

I refilled mine about 2-3 weeks ago. Man was it cold a few days after I did it, but now its back down to around normal I guess. It still is cold, but not nearly as cold as it was when I first refilled it. wow.
 
G

gmcturbo

Active member
Re: A/C diagnoses

you'll need to get a retrofit kit. it has service port adapters to the 134a style and oil.
 
berzerker

berzerker

wookie
Re: A/C diagnoses

to retrofit the sytem for 134a you will first , evacuate the system, replace all fitting o -rings , change reciever drier, and high and low pressure shradder valve fill fittings and then pull vacumn on the system. add 134a oil then charge system.
 
Bill Z

Bill Z

Donating Member
Re: A/C diagnoses

Has your air conditioner ever worked? My son had a problem with his truck. It seemed that someone had installed a new heater core and hooked up the vacuum lines wrong. So the doors inside the air box weren’t opening. This was easy to figure out because there wasn't much air coming out of the vents and what there was was hot.

Remember, on these trucks the hot water is always running through the heater core. It is only the doors that direct the blower air through ether the hot or cold side.

If it is low on Freon most Wal-Mart service areas will tell you that it is low for nothing. Just say that you don't want it fixed.

Good luck.
 
Tydriver

Tydriver

TurboLS6 Powa'
Re: A/C diagnoses

berzerker said:
to retrofit the sytem for 134a you will first , evacuate the system, replace all fitting o -rings , change reciever drier, and high and low pressure shradder valve fill fittings and then pull vacumn on the system. add 134a oil then charge system.
Click to expand...

:stupid:


One other thing to consider, replace the orifice tube as well, or at the least, check for contaminants if you DO disassemble/convert to r134a. There are even places that sell conversion pieces for the orifice tube as well. I've read that there is a different tube for r12 vs r134a.

HTH,
 
turbodog

turbodog

Donating Member
Re: A/C diagnoses

Just went thru this last weekend. System leaked months ago, so I just threw in some PAG oil and 134 as a temporary fix. That leaked out, too. Charged it a week ago so the wife could drive it , but it had leaked out by the next morning.

So, I bit the bullet, bought a new dryer, orifice tube. Turns out the fitting from the hose (the one that runs right freaking over the battery) to the dryer was completely loose! Seems whenever I was bending the hose out of the way to R&R the battery, it was loosening that fitting.

So, I stuck in the new parts, rented a vacuum pump, and pumped it down. Rigged a vacuum guage from my MytyVac and an old R12 filler adapter (fits on the pressure switch port of the dryer). Verified it was holding vacuum for 1/2 hour. No leaks. Pumped vacuum for another 45 min (gets all the moisture out) then charged it. Had to guess on how much oil had leaked out, so put in 1/2 can (4 oz) plus 2-1/2 cans of 134, checking low-side pressure. Woo-hoo! Blows cold now.

The key is to pull vacuum, then stop the pump (seal the port) and watch the vacuum guage. If it's leaking vacuum, it will leak out the freon. In my case, it was the loose hose fitting to the dryer. HTH
 
TYRODD

TYRODD

My ass. Look at it.
Re: A/C diagnoses

I just recharged mine an hour ago, gotta have A/C for all that damn humid KC heat! :D
 
NecroWolf

NecroWolf

lost marbles member
Re: A/C diagnoses

actually for the retrofit you'll mostly need to get your system vacumed down and put the new fitting kit on it. at the dealership we used to convert them all the time, fix the leak and fill it with the 134a. we actually just kept a set of fittings around and reused them. the ac would always blow really cold after we were done. a lot of times the leaks are o-rings that have dried out. or lines vibrated loose. and as far changing the oil if your system is leaked down you can buy the cans at the parts store that have the oil already in them. it's really simple once you find a leak. if you can find a vacum pump you can jump the compressor so it runs and then crack the fitting on the high side and it'll pump out the air and build up vacum on its on.
 
mattw

mattw

Active member
Re: A/C diagnoses

How much vacuum do you have to pull to purge the system? Also, how much did it cost to rent the vacuum pump?

Thanks,
-Matt






turbodog said:
Just went thru this last weekend. System leaked months ago, so I just threw in some PAG oil and 134 as a temporary fix. That leaked out, too. Charged it a week ago so the wife could drive it , but it had leaked out by the next morning.

So, I bit the bullet, bought a new dryer, orifice tube. Turns out the fitting from the hose (the one that runs right freaking over the battery) to the dryer was completely loose! Seems whenever I was bending the hose out of the way to R&R the battery, it was loosening that fitting.

So, I stuck in the new parts, rented a vacuum pump, and pumped it down. Rigged a vacuum guage from my MytyVac and an old R12 filler adapter (fits on the pressure switch port of the dryer). Verified it was holding vacuum for 1/2 hour. No leaks. Pumped vacuum for another 45 min (gets all the moisture out) then charged it. Had to guess on how much oil had leaked out, so put in 1/2 can (4 oz) plus 2-1/2 cans of 134, checking low-side pressure. Woo-hoo! Blows cold now.

The key is to pull vacuum, then stop the pump (seal the port) and watch the vacuum guage. If it's leaking vacuum, it will leak out the freon. In my case, it was the loose hose fitting to the dryer. HTH
Click to expand...
 
turbodog

turbodog

Donating Member
Re: A/C diagnoses

mattw said:
How much vacuum do you have to pull to purge the system? Also, how much did it cost to rent the vacuum pump?

Thanks,
-Matt
Click to expand...

I pumped down to 27 In Hg vacuum, for about 20 min, then stopped, sealed the ports and waited 1 hour to see if there was a leak (reduction in vacuum reading). Vacuum was stable, so I pumped for another 45 min (this causes water in the farthest corner of the system to evaporate and get evacuated), then put in freon.

I rented the pump at a local yard for $15. They sell for around $300. If I have to do it again (and since I'm now living 300 mi from that rental yard), I might try a venturi vacuum running on compressed air. That should pull it down to ~ 22 - 23 in Hg Vac. I would think anywhere from 22 to 25 in Hg Vac would be good enough. The main purpose is to get moisture out of the system, so lower vacuum over a longer time should work. But, the pump has to keep pulling for the whole time or else the water evaporates, but doesn't get evacuated. HTH.
 
Tydriver

Tydriver

TurboLS6 Powa'
Re: A/C diagnoses

turbodog said:
I might try a venturi vacuum running on compressed air. That should pull it down to ~ 22 - 23 in Hg Vac. I would think anywhere from 22 to 25 in Hg Vac would be good enough. .
Click to expand...

This is what I did, you can pick them up cheaply from Harbor Freight..


Todd
 
turbodog

turbodog

Donating Member
Re: A/C diagnoses

Yup. The same basic unit, but without the 134a fitting is less than $10 in the latest catalog.
 
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