Freshly charged AC, no cold air? - Chevelle Tech
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post #1 of 15 (permalink) Old Sep 3rd, 18, 7:41 PM Thread Starter
 
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Freshly charged AC, no cold air?

Factory 70 AC system, other than compressor, freshly charged but getting no COLD air. Shouldn't I be getting cold air some where? The clutch is kicking on, blower motor works...........just no cold.
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post #2 of 15 (permalink) Old Sep 3rd, 18, 9:18 PM
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Re: Freshly charged AC, no cold air?

What are your high side and low side pressures on the gauges? How much refrigerant was added? How much oil?

Rick

1970 El Camino under Reconstruction - 5.3L LS VORTEC Engine and 4L60E Transmission
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post #3 of 15 (permalink) Old Sep 3rd, 18, 10:17 PM Thread Starter
 
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Re: Freshly charged AC, no cold air?

Quote:
Originally Posted by B52bombardier1 View Post
What are your high side and low side pressures on the gauges? How much refrigerant was added? How much oil?

Rick

I had a speed shop charge the system, so not sure on pressures. As for oil, I recall 6oz and 2oz of oil. The only thing I was unsure of was how much was in the compressor after when it shipped; but it was "wet".


Is there anything in the Heat/Cool system that would "prevent" the production of cold air? New compressor, new expansion valve, new POA for 134a, all wires that I know of are hooked up.
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post #4 of 15 (permalink) Old Sep 3rd, 18, 10:38 PM
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Re: Freshly charged AC, no cold air?

I would think that if a shop charged it should be close to correct and working. If not they should have said something to you and tried to pry more dough from your wallet.

Since you don't have gauges or pressures, feel around on the aluminum parts of the system and let us know if any show signs of cooling. Some areas should be hot while others cool.

I would also try to block off the coolant flow to the heater temporarily. Sometimes the heater doors leak and will kill any cooling potential/

I think you should take it back to the shop that did the work or pick up a set of gauges. Without gauge readings, we'll just be throwing out guesses.
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post #5 of 15 (permalink) Old Sep 4th, 18, 12:13 AM
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Re: Freshly charged AC, no cold air?

There should be a shut off valve in the heater hose to the heater core. Sometimes these leak and bypass coolant into the core when the a/c is on defeating the cooling. Some are vacuum controlled and in 70 I think they were cable controlled. Maybe the cable isn't closing that valve. If you don't have that valve in the heater hose, you could install a manual ball valve to positively close the coolant flow to the heater core.

The evaporator and heater core live in the same airbox separated by a cable controlled blend door. If the seals are bad or the door isn't closing fully, you'll lose cooling capacity. Shut off the hot coolant flow to the core is a way around this without having to tear out the a/c box.
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post #6 of 15 (permalink) Old Sep 4th, 18, 2:20 AM
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Re: Freshly charged AC, no cold air?

Made a mistake on the above post. 70 Chevelle had a vacuum contolled coolant flow valve as seen below.
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post #7 of 15 (permalink) Old Sep 4th, 18, 10:45 AM Thread Starter
 
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Re: Freshly charged AC, no cold air?

Good input, hot water has been "blocked", no cold parts found by touch. I am hoping it was/is just under serviced?????? I assume it could be a leak, simple mechanics mistake?????? When the rain dies off I will get to the shop and verify. Will also keep progress posted, as I do appreciate the input.
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post #8 of 15 (permalink) Old Sep 4th, 18, 11:09 AM
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Rame
 
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Re: Freshly charged AC, no cold air?

When I pulled the evaporator core in my 72 it had a rat nest of trash and leaves in there, it was enough to block any air flow through it.

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post #9 of 15 (permalink) Old Sep 4th, 18, 12:15 PM
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Re: Freshly charged AC, no cold air?

Quote:
Originally Posted by Don Crow View Post
Good input, hot water has been "blocked", no cold parts found by touch. I am hoping it was/is just under serviced?????? I assume it could be a leak, simple mechanics mistake??????
Did it work when you first got it back from them? If it didnt, dont go back there. Either it was undercharged, or you have a leak.

Start at the compressor, and follow the lines around until you get back to the compressor looking at all of the connections, condenser, etc. if you have a significant leak, you should notice some oily goo. Look around the clutch on the compressor....a popular place for leaks is the shaft seal on the big A6 compressors.
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post #10 of 15 (permalink) Old Sep 4th, 18, 1:03 PM Thread Starter
 
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Re: Freshly charged AC, no cold air?

Everything, other than the case, on this system is brand new; heater core, evaporator, hoses, lines, condenser, drier, POA, expansion valve, etc. I have to tell my self it's a leak, as I have faith in the shop I took it to.
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post #11 of 15 (permalink) Old Sep 4th, 18, 1:22 PM
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Re: Freshly charged AC, no cold air?

Need to see what the low side and high side pressures are.
How about buying or borrowing a set of gauges and checking it yourself?

Looks like you are close to the Wichita Area Chevelle Owners
WICHITA AREA CHEVELLE OWNERS
Great bunch of folks there, I bet one or more of them would help you out if you ask.

By The way, they are having a great Chevelle/El Camino show this week end if you didn't know.
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post #12 of 15 (permalink) Old Sep 4th, 18, 8:37 PM
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Re: Freshly charged AC, no cold air?

Also:::::
Just so you know, I have done a few R-12 to R-134 conversions in 1970 chevelles with factory A/C. I have also done my 1970 SS 454 Sta. Wgn.
Some items that must be changed,,,, If you want the A/C system to function as it should.l
FIRST: The P.O.A. valve MUST be adjusted for R-134.
SECOND: R-134 builds more heat than R-12, I replaced my org. 1970 condenser with a FACTORY FIT -1970 / 72 Parallel Flow condenser. ( This condenser uses ALL the factory nuts,, bolts,, and brackets., I have one on mine) WHY? The G.M. condenser with the Appx. 3/8" dia. tubes WILL NOT cool the R-134.
Third: Using the old style A-6 Compressor is OK,,, BUT you will recharge it just about every spring. WHY? The R-134 molecules are much smaller than the R-12s, So it will leak out of the front seal and the Org. R-12 hoses.
Fourth: You need a dryer that is R-134 compatible.
Fifth: I installed R-12 / R-134 compatible hoses.
Sixth: The org. 1970 C-60 system takes a R-12 charge of 60 Ozs. When you convert a C-60 system to R-134- The Charge of R-134 should be 48 Ozs.
Last year I replaced my A-6 compressor with a new style Alum. compressor that uses " ALL THE ORG 1970 NUTS BOLTS & BRACKETS & HOSES ". It is the same size as the A-6 and designed to operate on R-134
Getting the 1970 style O.E.M. A/C unit to operate as it did in 1970 will cost some money. To convert a 1970 C-60 system to R-134, Be prepared to spend at least $1000.00.
After many years of trying to get cold air CHEEEEEP in my Red 70. I did it right. Having your A/C system to function well,,,, IT IS NOT cheap.
If any one trys to tell you a different story on how to get a 1970 Chevelle A/C system to function well, Also they may say, You do not need to do all of the above.
Myself and other T-Chevelle guys have converted some early G.M. A/C units. It cost a lot of money to be KOOL
Using the above ideas and skipping nothing, I get 38 to 43 degrees out of my center vent and I HAVE NOT touched the A/C unit in over two years.
Again, " Being KOOL Aint Cheap ".
Bob
P.S.
Over the years I screwed around trying to get cold air cheap. So I spent some cash and its over and done with. If you are converting R-134 do it CORRECT or dont even start.!!!!!!!!!!!!!!!
Trivia, To account for a bad seal in heater doors or a bad 1970 Vacuum operated water valve, I went to Lowes and I have a water " Shut Off Valve " mounted near the firewall so you KANT see it, I painted it black.
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post #13 of 15 (permalink) Old Sep 15th, 18, 11:54 PM
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Re: Freshly charged AC, no cold air?

Around here you can rent a manifold gauge set for free from autozone. It would be worthwhile to check the charge yourself. Considering it was just repaired by a shop, I would expect a full charge with zero leaks, but ya never know.

What kind of cooling fan are you running? The condenser may need more airflow if youre just testing the system out by idling, but even idling you should get some cold air.
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post #14 of 15 (permalink) Old Sep 18th, 18, 10:52 AM Thread Starter
 
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Re: Freshly charged AC, no cold air?

Just to let those of you who had interest at ease, it was not the shop, the charge or fault of anything other than a bad expansion valve (right off the shelf). Pressures were good statically. When you engaged the compressor, the low side went to zero......changed that valve and wammo! Cold Air! Happy camper!!
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post #15 of 15 (permalink) Old Sep 18th, 18, 2:38 PM
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Re: Freshly charged AC, no cold air?


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