A/c gets warm at times?

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A/c gets warm at times?

July 12, 2012, 11:45:58 PM

Okay this is on my 87 3.8 Bird. I've done my low buck A/c system overhaul. I did that last year and only installed 2 cans of freeze 12. It was cool to cooler last year but money was tight so I couldn't afford another can to top the system off. Worked great every time I used it last summer for a system that was 1/2-2/3 of a can low on charge. So fast forward to this year. I had to money so I picked up another can of the freeze 12 and gave her the top off, Put in the whole can and pressures high and low were in range for outside temps running freeze 12. So the air is COLD COLD. So same day I topped it off had to make a trip 30miles one way. Took the bird cause after the top off the A/c was so nice and cold. got about 20or so miles down the road and this road has large mountains for my area. On these big hills or even giving it lots of gas just to get out and by someone kicks off the compressor. I figure the WOT relay is kicking out the clutch. Even after I have got to the top of the hill/pass and let off the gas considerably still A/c air is warm. I turn it off and back on still warm. Then turn it off for say 5min probably and flip it back on and Air gets cool quick. SO I was thinking maybe the A/c WOT relay was sticking, but doing searches on A/c that does this sort of thing and they say it probably freezing up. I would test when it happens but only seems to happen when its a I can't stop and risk being late, also only seem to happen when its HOT HOT outside today it happened when it was 97F but I could never get it happen on the way home when it was 87F same road same hills. I may not be Mister pro auto a/c or a HVAC guy but. Wouldn't it freeze up easier when its cooler outside that when its hotter? Anyone with any idea feel free

Thanks for lookin
Stuckman

A/c gets warm at times?

Reply #1 – July 13, 2012, 12:02:54 AM

Think of it as like a window unit A/C, when it's been running and you turn it off you can't immediately turn it back on due to system pressures being high you have to wait for pressures to equalize before the system will function properly again.

A/c gets warm at times?

Reply #2 – July 13, 2012, 12:23:12 AM

Like that input makes sense in my head and I say I agree except that is new modern stuff. This is old school simple pimple yes you can blow it up on your own ass if you not careful setup. I still agree but I turn on ac that sends power to the A/c relay that if the pressure switch(old school only has low pressure switch)shows there is enough pressure it turns on compressor. Then if the pressure gets low to low pressure switch, or you hit enough throttle to trip WOT relay it shuts it off unless you turn it off inside the car. So thank you so much for the reply and totally see your point but even old window A/c off and on at any time. Maybe they tell you not to but that it how old stuff works .

Thanks again
Stuckman

A/c gets warm at times?

Reply #3 – July 13, 2012, 06:04:55 AM

Probably just a little too much freon causing too high of a pressure when it's hot. Have those pressures checked for the freon you have. It takes less quantity for Freeze12 than for R-12 to get the system to cool. I use Envirosafe and it takes a lot less than 'normal'.

A/c gets warm at times?

Reply #4 – July 13, 2012, 07:01:42 AM

OK first off Freeze 12 would not be my choice of freon. It is a BLEND. 81% R134A. So right off the bat you need to charge 10-14 % lower than with R12 as your system was designed for. Being you have a CCOT system you most likely have a moisture issue in the system. Not 100% but that is what it sounds like. Did you suck the system down for 24 Hours?? If not you just might have a moisture issue. Also is the condenser fan coming on with the AC??? If not check that out. Also what are your manifold readings at 1400 Rpm HIGH FAN MAX AIR SETTING and Discharge TEMP READINGS. Without this info i can only guess an answer here it is!!! OVER CHARGE OR MOISTURE ISSUE. Remember Always starve a conversion system. Never use the old amount of designed freon capacity. And monitor the low side readings with a temp chart for the freon you are using. Good luck!!

A/c gets warm at times?

Reply #5 – July 13, 2012, 07:21:40 AM

First off, IF you're freezing up you'll lose airflow from your vents, because the water that condenses on the evaporator freezes and obstructs airflow from the blower. This is because you're lo side pressure pulls below 20 psi and the clutch stays engaged, overcooling the evaporator. This is not what's happening to you. The first thing to do is get it to not work, once it quits working, visually verify clutch operation. If it's warm and the clutch is engaged, verify airflow from the cooling fan, then verify your hi and lo side pressures while it's not working. If the clutch is NOT engaged, disconnect the clutch and verify power at with a test light, preferably with a high amp test light made from a headlight bulb. If there is voltage and the clutch is NOT engaged, you've got a clutch field coil that's heat soaking and giving up, if you DO NOT have power, verify lo side pressure is in range of the low side cycling switch OR disconnect the lo side switch and install a FUSED jumper wire and observe whether you gain power at the clutch connector or not.

But as an aside, consider that you've been can charging which is a fundamentally flawed idea, next you've been using an R-12 substitute which is down right dumb. My BEST advice is to open your system and let it sit open for a couple of hours(to save your pro from wrecking his a/c machine), THEN take it to your pro to be retrofit to R-134a, you're pro will vacuum the system so that you don't have air and refrigerant in the system together (pure fail, and the most probable cause of your troubles) and he'll charge the system to full (which he knows because he has a machine to measure charge weight) and install UV leak dye, so that the next time it blows warm he can dye light it and FIND AND FIX THE PROBLEM that's causing it to leak in the first place. 50% of my workload for the last 2 months has been a/c work, and I've seen just about everything. You can't properly diag a system that's been shaged with until you've unshaged it.

A/c gets warm at times?

Reply #6 – July 13, 2012, 08:55:19 AM

Quote from: TOM Renzo;394286

Did you suck the system down for 24 Hours??!!

Wow! Does it need to be that long? That would prob kill my little pump.

What is the min time necessary to do the job?

A/c gets warm at times?

Reply #7 – July 13, 2012, 10:43:04 AM

Under normal conditions, you don't need to pull a vacuum that long. Typically, I'll pull down and hold 10 minutes, then maybe 10 more for leak test, however, when somebody brings me something where the system has been open for any period of time, I'll pull vacuum for much longer, like an hour while I'm at lunch or 2 if I pull the orifice and don't like what I see.
If there's air in the system along with R-12 substitute product, then Tom's probably right about the presence of moisture, where there's air there's water, even if only a little.

Don't can charge. Don't screw around with blended refrigerants or substitutes, and for God's sake DON'T CHARGE PROPANE. Refrigerant blend products and substitutes are trouble in a can, and, if somebody doesn't know it's in there and they hook up a machine, its several thousand dollars to replace the machine. There's no safe way to remove it from a car that doesn't either vent it to atmosphere or wreck equipment.

A/c gets warm at times?

Reply #8 – July 13, 2012, 11:30:47 AM

First off let me Thank Everyone for there input.

I am aware of the need to use less of replacement refrigerants than what it had for the original R12. So Yes I should go back out there when its hot hot and keep gauges on it watch the pressures. Yes I did pump the system down when I got it all working last year. I own a robin air Vac pump so I hooked it up and ran it for 1.5hr. I never really get less air from the vents just it starts getting warmer as you can tell the A/c isn't on. Yes I'm using off branded freeze 12 not R12 or R134a.I've used freeze12 in 20 or more r12 systems it has done great for mine and others, and yes I did attach the fittings and labels on there cars. It is a good works better in R12 than r134 from my personal experience. I don't have a problem with it and I can find it. I don't have the lic to get hands on real R12,or R22. I have a couple of buddies in the HVAC business and had them give me there opinion on the stuff before I used it. They both told me should work great. Take that I do all my own work and by installing the Freeze12 fittings and labels on the cars that should tell all the system doesn't have there recoverable refrigerant in the car. Purge the system and start over ONLY as a LAST RESORT. I don't worry about wrecking pro service guys/gals recovery machines plain and simple "I don't ever ever ever go there for them to work on my stuff". only time I take any of my autos to a shop is if I'm outta town. I do all my own work I even do work for several other of my friends and family. I worked in auto shops and parts stores and been all around cars/trucks. So flylear45 I plan working through the first part of your post. Get it to stop working and test clutch coil wires like you said. Thanks again guys for all the help and ideas.

Thanks for lookin
Stuckman

A/c gets warm at times?

Reply #9 – July 13, 2012, 09:45:38 PM

We normally suck down for a min of 6 hours. Also it depends on the vacuum pump you have. If your pump cant bring down the system to 29.9 your pump will not boil out the moisture. Remember if the system is loaded with moisture the pump has a big job to do. I always replace the canister. Their is nothing wrong with installing RA134a. Just remember you have to charge lean. Actually you can gauge you charge by the low side. Normally you want 32-38 at 1200RPM. This can be confirmed by your low side reading. I am certified AC for many many years and i will tell you right now a converted system properly charged and working properly is just fine. You cant buy R 12 because you lack a license. But the charts will point you in the right direction of efficiency of the system. Normally a conversion is always a good thing for a non licensed individual. But remember you cant vent and be discrete. Because an un licensed service tech is not allowed to service AC systems.

Their is nothing wrong with can charging. as the matter of fact an absence of a machine and can charging is your best bet. Because you can basically tell how much material is in the system. Simple the can has the weight on it's label and thst is an exact amount. For example if your system takes 2 LBS and you have two 16 OZ cans you are right on. Their is nothing wrong with can charging as long as you know how to read the manifold gauges and tally up your can charge.

A/c gets warm at times?

Reply #10 – July 13, 2012, 09:55:56 PM

BEST advice is to open your system and let it sit open for a couple of hours

Do not take this advice!!!! YOU CANT VENT BY LAW. If caught you will suffer a BIG FINE. Any AC guy worth his grain of salt would never advise this NO WAY NO HOW. It also will let Moisture in the system. DO NOT DO THIS IT IS DEAD WRONG!!! Also testing the integrity of a system for leaks by applying vacuum is totally incorrect. A trace gas shoild be used with electronic leak detection. Dyes are ok for big leaks but dye is primative at best. It is almost impossible to find a slow leak with DYE. Some claim it is the cats ass, But in reality al leak tester is best.

Free Air Displacement: 10 CFM
Number of Stages: Two
Factory Micron Rating: 20 microns
Intake Fitting: 1/4in. and 1/2in. MFL
Oil Capacity:16.5 OZ. (488 ml)
Motor Size: 1/2 HP
Voltage: 115V, 60Hz
Weight: 38 lbs
Dimensions: 10in. H x 5-5/8in. W x 16in.L (27.2cm x 14.2xm x 41.9cm)
Here is a good pump with a very good micron count

A/c gets warm at times?

Reply #11 – July 14, 2012, 09:10:21 AM

There reason I dislike can-charging, Tom, is that not everybody who does it has a vacuum pump, and when you can-charge a dead system without pulling a vacuum, you're leaving the air in the system. It's possibly not a big deal if the system is simply low, because that system hasn't started gulping air, however, if the system IS low, you can't have any idea how much refrigerant is actually in there before you start. But I agree that there is no good reason NOT to use straight 134a, last time I checked you could buy it off the shelf at Walmart. R-134a's behaviors and interactions are a known quantity. It's stable, it's reliable, it's just the right stuff to use. I believe they even have dye charged cans.
As for low side pressures, if it's nor super hot or super humid, you should be pulling the low side down to mid 20's before the cycling switch kicks out the clutch, and then rising to mid 40's before it kick it back on. If not, the low side switch on our cars is adjustable, but you've got to adjust carefully. Not something you'd have to do on a system that still carries R-12, as far as I know, but once you switch to 134a (or just about anything else) you may have to watch your pressures to decide if you need an adjustment. If it IS hot and humid, you may not be able to pull down that low period, and the clutch might just stay on.
Verify your cooling fan. If your fan isn't working or the fan clutch is freewheeling, you'll get a hot condenser. Your high side will rise above 300-350 and your low side will be unable to pull low enough to carry heat out of the cabin.

A/c gets warm at times?

Reply #12 – July 15, 2012, 12:06:38 AM

This is all you need to find out what the charge is. That is why a manifold is used. Note the system pressures and temps between R12& RA134A

http://www.aircondition.com/pressure.htm

I have thought about this problem and i would change the CCOT SWITCH Just to get that out of the way. Basically the two FREONS 12&134 are quite similar on the low side if you look at the tables. I have converted mann systems with excellent results.

A/c gets warm at times?

Reply #13 – July 15, 2012, 07:47:44 AM

Venting is not legal, that's correct, but would you seriously ask someone to sacrifice their a/c machine? As for moisture from venting, that's probably true, but considering that we wouldn't ask someone to sacrifice their machine, what I would say is that you can't make an omelet without breaking some eggs. Vacuum the system longer. That's what you have to deal with when somebody installs a non-recoverable refrigerant. What else are you going to do?

A/c gets warm at times?

Reply #14 – July 15, 2012, 06:26:50 PM

First off you need some training on ac systems. Have you ever heard of a freon identifier. If you are truly an ac technician you should know this and have one ??? Second We in the business always have this sort of issue. How can you tell what freon is in a system. I cant tell. And you cant VENT PERIOD. So as a novice you have to have the system recovered and vacuumed down. Then charge to the proper amount and check the gauges and vent TEMPS. This is what the industry is all about. That is why i charge BIG BUCKS for AC repairs. If not sweat your BUTT OFF. Thanks