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DakotaSport
Dodge Dakota
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4/19/2005
17:58:49
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 Subject: AC Question
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When i turn on my air, my A/C compressor only turns on when i have max A/C going. From my understanding that is only supposed to be used for a little bit, and when i change to the feet and head setting, the ac compresser turns off. Is this normal or am i just low on the refriderant (sp)? I have a 00 with a 4.7.
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chris
Dodge Dakota
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4/19/2005
19:45:41
| RE: AC Question
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well when the a/c is on, is it cold?? if it is then ur not low on refrigerant. the setting ur turning it to, does it have the little a/c snowflake symbol next to it?? if not then ur a/c should not come on. the only exception is when u have it on defrost. i dont think defrost has the little snowflake. and if the setting does have the snowflake, then mayb a problem with the switch? u would have to do some diagnostics.
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DakotaSport
Dodge Dakota
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4/19/2005
22:22:51
| RE: AC Question
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Ya it kicks in with the ac symbol, so it sounds like its all good. I just got the truck in November from Caramax, hopefully they checked everything out like they say they do. It sounds like im just low on the refrierant then. Thanks
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Big Ed
Dodge Dakota
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4/20/2005
06:38:51
| RE: AC Question
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Remember this though, if its low on refrigerant, you have a leak. The refrigeration system is a closed system and the refrigerant will last "forever", so if its low, theres a leak. Refrigerant doesn't grow weak, its either in the system or has leaked out. Look for oily areas around fittings on the refrigerant tubing/compressor and pressure controls, ect. The oil in the compressor mixes with the refrigerant and travels throughout the system. Soap bubbles are a good way to check for leaks too.
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chris
Dodge Dakota
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4/20/2005
21:54:37
| RE: AC Question
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well if u have a leak, get it recharged with dye. that way u will be able to find the leak easily with a uv light and glasses. and also, if you do have a leak, pray its not the evaporator.
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Big Ed
Dodge Dakota
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4/21/2005
07:00:14
| RE: AC Question
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The dye works great, BUT, our experiance at work has shown that the dye, while mixing with the oil and refrigerant, has created more problems in that it reacts with gaskets/o rings and on hermetic compressors, it has shortend the life of the compressor by eating the insulation on wire windings. Best bet, have it pressurized with CO2 and a trace or R22, use an electronic leak detector or soap bubbles.
Chances are, its a very small leak and a recharge will last your the summer. 134a is cheap and can be bought at Wal Mart. Just be sure to charge it on the low side.
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chris
Dodge Dakota
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4/21/2005
17:34:09
| RE: AC Question
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actually at my work, the price of 134a has gone up alot. i think its now up to around $25/lb. i dont know about the stores tho. also if you buy it from a store, stay away from the refrigerant that has "stop leak" added to it. it mite stop the leak but can also clog up your whole a/c system all together.
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Big Ed
Dodge Dakota
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4/21/2005
20:40:10
| RE: AC Question
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134A is not even close to that price, maybe your confusing it with R-11 or R-12?
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acdak
Dodge Dakota
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4/21/2005
20:57:37
| RE: AC Question
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ok folks, here it is
Auto Ac units are designed to leak, I'll make my classroom presentation short. refrigerators have a sealed system,evrythin is in a metal can, cars have a pulley on the compressor that freon oil leaks past to lubericate the bearing on the shaft. that's why they banned R-12 because cars ac compressors are made to leak and every 5 years or so you have to add about 10 ounces.
It's no big deal been doing it for years
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acdak
Dodge Dakota
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4/21/2005
21:04:41
| RE: AC Question
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oh a little tip. run your ac on max reciculating for about 10-15 minutes. Put your fingertips to the coldest vent- usually in center of dash - your fingertips should tingle from the cold air or use a probe thermoeter for a 20 deg drop from ambient. Some jap cars ac air comes out at 40 degrees, american cars are usually around 55 degrees.
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Big Ed
Dodge Dakota
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4/21/2005
21:49:32
| RE: AC Question
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acdac is SOOOOO wrong, they were and are never designed to leak, ever. R-12 has been replaced by 134A and 404A & B because of the clorine in it leaking into the atmosphere, putting that huge hole in the ozone. (to me, a money making ripoff of big buseness, you can put all the clorine you want in your pool and it evaporates into the atmosphere) Semi Hermetic compressors for walki in refrigeration are belt driven and they never leak if maintained properly. The reason leaks are more common in the auto industry is because rubber hoses have to be used because of the movement of the engine and all components attached to it when its running. The connections vibrate, hoses crack and due to all the vibrations, leaks develop. Compressors rarely leak at the clutch/belt area, its almost always at rubber to metal joints.
acdac, you need to go back to class.
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GraphiteDak
GenIII
 
4/21/2005
22:15:25
| RE: AC Question
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I haven't seen any semi hermetic comressors that was belt driven.
Pump and motor is intergal on those.
I know like 40+ years ago they ran them with belt drives :) but that was WAY before I was working on them.
Your belt driven car compressor CAN leak slowly through the front seal around the shaft. Especially if you don't use it for long periods. That's why using defrost is a GOOD thing in the winter, besides it removing humidity.
If it's just a LITTLE low you could top it off and try using it. That's the CHEAPEST thing to do to see if running it will condition the front seal. Then if it continues to leak start to worry about it. It can be a bitch if it's not obvious or where a electronic leak checker can detect it.
I too have stuck R22 in systems for leak checking. That's because I've always got over 30Lbs of it at any given time. Just don't use any USED recovered r22 that would have the wrong OIL in it. That could contaminate your system.
Add just enough like maybe a Lb of it at most and back that up with Dry nitrogen to bring it to a good 300 PSI (and hope that doesn' hurt your evap since it's not tested for that pressure like your high side components are).
Dye sucks and should ONLY be used if a last resort. Oh. and there's no "windings" to be harmed by dye in a car system. It's got no motor windings inside it like a semi-hermetic, hermetic, scroll, or rotary electric motor driven comressors do. but dye still sucks in the metering devices and compressor valves.
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Big Ed
Dodge Dakota
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4/22/2005
06:59:59
| RE: AC Question
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Never said auto compressors had windings, just stated that the dye has been known to cause problems with most a/c systems, especially seals. Its standard practice to leak check with nitrogen and R22 (trace) when using electronic detectors. 100 psi is more than enough pressure to leak check any system. Just be sure to completely vacuum out the system and charge it with fresh 134A. Belt driven compressors are still used in alot of walkin refrigeration systems. We have 4 units at the VA where I work.
And yes it can leak around the seal, BUT ITS NOT SUPPOSED TO unlike what acdak says. All refrigeration systems are "closed" period. Any noncondesables that get into the loop will cause the refrigeration cycle to fail. End of story.
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acdak
Dodge Dakota
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4/22/2005
07:55:28
| RE: AC Question
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just like air molecules leak thru the rubber in your spare tire and occasionally you need to add air.
Freon molecules do very slowly migrate thru the rubber hoses - another slow leak source for the r-12 to get out.
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dkguy
Dodge Dakota
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4/22/2005
08:06:17
| RE: AC Question
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heck i seen bubbles on the rubber hoses, didn't see any holes or cracks but with soapy water i got real slow bubbles coming up. freon detectors may or may not pick it up but they're not as messy as water. if the hose is oily, it's leakin or if there is a oil slick on the bootom of the hood the front seal is leakin bad.
They realized cars leak, so they may as well leak safe? r-134a versus unsafe r-12
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iLUVfatCHICKS
Dodge Dakota
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4/22/2005
08:16:25
| RE: AC Question
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heck, you ort to see the bubbles my fat chick makes when she's under water. i believe theres some crack there somewhere.
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Bob Lincoln
Dodge Dakota
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4/22/2005
10:38:45
| RE: AC Question
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"just like air molecules leak thru the rubber in your spare tire and occasionally you need to add air."
Whoa. The primary source of leakage is the Schrader valve itself, not through the rubber wall.
"Freon molecules do very slowly migrate thru the rubber hoses - another slow leak source for the r-12 to get out."
Yes, but it's not DESIGNED to leak, it just happens.
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GraphiteDak
GenIII
4/22/2005
12:28:36
| RE: AC Question
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Big Ed... I didn't see where you said "AND ON hermetics the (dye) eats the windings". :)
I must have been speed reading that part when I assumed you were still talking about car A/C's.
Some cars have gone over 10 years without needing any charge. And some people just have problems almost every year.
The EASY fixes are when a hose simply breaks or soemthing. The small leaks no one finds are the bitch.
My friend lives on the EAST valley. I live on the West (Scottsdale and Surprise, AZ) so we never hooked up to look at his Astro Van's a/c problem.
Well He spent almost $1000 on it last summer and they never fixed it. Each time they said it was the compressor leaking. Then this, then that. Then now they say it's his rear evap. But am not sure!!!! He ran out of time having to take it in and still goes with no A/C and almost $1000 lighter in his pocket!
One of these day's he'll bring it over to my house when he's dying this summer at 115 degrees!
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Big Ed
Dodge Dakota
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4/22/2005
16:40:14
| RE: AC Question
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Right on Bob Lincoln. The shrader valve is a common area where leaks occure. With the kwik connect setup on 134A systems its less likely but still happens.
I hear ya Graphit, 1000 bucks and its still dicked up. You know, if its a leak that looses its charge in a week or so, you should almost be able to hear it. Small leaks, you know, when you need a charge every year or two, its cheaper to just give it a shot when the charge drops then to spend all that mulla. You ever hear about the 280 A/C? 2 windows down and 80 mph!!!!
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Big Ed
Dodge Dakota
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4/22/2005
17:44:34
| RE: AC Question
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Also, you don't want to overcharge it either. Some cars have sight glasses but a good rule of thumb is (if you don't have gauges) is when the suction line gets cold near the compressor, its just about right. 35 lbs of back pressure will give you a about a 38 deg. evaperator temp. for 134A. R-12 is about 35 deg. at 35 psi back.
Overcharging can make your head pressure go way up, then you'll deffantly find the leak!!!! (when a hose blows)
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GraphiteDak
GenIII
4/22/2005
21:46:44
| RE: AC Question
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Big Ed. you must be talking about the "Beer can Cold" superheat method :)
Hold that suction line until it's as cold as your freshly opened beer in the other hand!
Of course gauges and a clamp on thermometer work good too.
When I first got into A/C, my boss (lots of experience) didn't even use sperheat. He used his HANDS. Now I can't imagine NOT using superheat/subcooling measurements. Although the variables are alot diff in Car A/C's.
Ever put hot shot (414B) or R409 in a car A/C? Boy that head pressure gets kind of scary :P
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