Another A/C troubleshooting question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Gene · 08-06-2008, 09:53 AM

Got a 71 Chevy with factory air, charged it last season and it just barely got cool afterwards. Now i'm trying to get it up and going this summer and here's the problem. The compressor kicks on and stays on, the line at the bottom of the evaporator is pretty cold but the air coming out of the vents is not. I know the door is in the right position because I can manually move the door and when I do that the vents blow hot! A freind told me that the expansion valve is dirty or stuck but I need some verification.

Thanks!

Andy4639 · 08-06-2008, 10:03 AM

When you did the recharge last summer did you pull a vacuum on the whole system? Before you charged it. If not you need to. A clogged POA valve or it's not working at all. Sounds like you need a good over haul on the whole system. The condensor could be clogged, evaperator there could be numerous things wrong with the system.

Gene · 08-06-2008, 10:06 AM

Quote:

Originally Posted by Andy4639

When you did the recharge last summer did you pull a vacuum on the whole system? Before you charged it. If not you need to. A clogged POA valve or it's not working at all. Sounds like you need a good over haul on the whole system. The condensor could be clogged, evaperator there could be numerous things wrong with the system.

Yeah, had a vaccum pulled when it was charged. It held and didnt lose vaccum.

Willys47 · 08-06-2008, 10:37 AM

make sure you don't have the hot water running through the heater core some times the valves dont close and it lets the hot water through and you can't cool down all that motor with the a/c system.

Gene · 08-06-2008, 10:53 AM

Quote:

Originally Posted by Willys47

make sure you don't have the hot water running through the heater core some times the valves dont close and it lets the hot water through and you can't cool down all that motor with the a/c system.

You know, that makes sense. I have a valve that is supposed to shut off the water to the heater core but it is not closing and letting hot water through to the core. If I bypass the heater core it should tell me if thats my problem. I'll give that a shot.

mrein3 · 08-06-2008, 12:59 PM

Quote:

Originally Posted by Gene

You know, that makes sense. I have a valve that is supposed to shut off the water to the heater core but it is not closing and letting hot water through to the core. If I bypass the heater core it should tell me if thats my problem. I'll give that a shot.

Or just manually shut the valve and wire it shut. Then you don't have to open your cooling system and have to burp it, etc.

Gene · 08-06-2008, 01:04 PM

Quote:

Originally Posted by mrein3

Or just manually shut the valve and wire it shut. Then you don't have to open your cooling system and have to burp it, etc.

Well, I bypassed the heater core and it still isnt blowing cold?? Should both top and bottom tubes to the evaperator be cold? Because only the bottom one is cold?

Willys47 · 08-06-2008, 07:22 PM

it should be cold after the xpantion valve

JimKshortstep4x4 · 08-06-2008, 08:39 PM

Does the sight glass have bubbles in it or does the refridgerant flow look good?

Jim

Botietruck · 08-06-2008, 08:55 PM

Gene, for what it's worth, if you have the original system and want to keep it that way, you will have a very hard time finding NOS parts.
I came across a company in Tampa FL that will recondition pretty much any a/c part you have. I sent my expansion valve to them and got it back in 3 weeks. It was completely reconditioned and refinished with zinc plating. It cost me $72.40 and that included shipping. That might be an option for you. Their name is Classic Auto Air Mnfg. Co. (813) 251-2356

08-06-2008, 09:53 AM	#1
Gene Registered User Join Date: Aug 2002 Location: Muskogee, Oklahoma Posts: 2,914	Another A/C troubleshooting question Got a 71 Chevy with factory air, charged it last season and it just barely got cool afterwards. Now i'm trying to get it up and going this summer and here's the problem. The compressor kicks on and stays on, the line at the bottom of the evaporator is pretty cold but the air coming out of the vents is not. I know the door is in the right position because I can manually move the door and when I do that the vents blow hot! A freind told me that the expansion valve is dirty or stuck but I need some verification. Thanks!

08-06-2008, 10:03 AM	#2
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Another A/C troubleshooting question When you did the recharge last summer did you pull a vacuum on the whole system? Before you charged it. If not you need to. A clogged POA valve or it's not working at all. Sounds like you need a good over haul on the whole system. The condensor could be clogged, evaperator there could be numerous things wrong with the system. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

08-06-2008, 10:37 AM	#4
Willys47 Registered User Join Date: Dec 2007 Location: Nanaimo B.C. Posts: 604	Re: Another A/C troubleshooting question make sure you don't have the hot water running through the heater core some times the valves dont close and it lets the hot water through and you can't cool down all that motor with the a/c system. __________________ I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!!

08-06-2008, 07:22 PM	#8
Willys47 Registered User Join Date: Dec 2007 Location: Nanaimo B.C. Posts: 604	Re: Another A/C troubleshooting question it should be cold after the xpantion valve __________________ I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!!

08-06-2008, 08:39 PM	#9
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Another A/C troubleshooting question Does the sight glass have bubbles in it or does the refridgerant flow look good? Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC Last edited by JimKshortstep4x4; 08-07-2008 at 05:22 AM. Reason: word change

08-06-2008, 08:55 PM	#10
Botietruck '71 chevy s.bed/s.side Join Date: Mar 2005 Location: Chesapeake, VA Posts: 1,571	Re: Another A/C troubleshooting question Gene, for what it's worth, if you have the original system and want to keep it that way, you will have a very hard time finding NOS parts. I came across a company in Tampa FL that will recondition pretty much any a/c part you have. I sent my expansion valve to them and got it back in 3 weeks. It was completely reconditioned and refinished with zinc plating. It cost me $72.40 and that included shipping. That might be an option for you. Their name is Classic Auto Air Mnfg. Co. (813) 251-2356 __________________ STILL PLAYS WITH CARS...AND TRUCKS!! Parents! Be good to your kids...they get to choose your nursing home! 250 I-6 with a 3 speed Saginaw and Borg Warner Overdrive...She's got overdrive! Last edited by Botietruck; 08-06-2008 at 08:58 PM.



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