| [GMCnet] dash air conditioner expansion valve [message #216443] |
Wed, 31 July 2013 19:31  |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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On my way home from Shawnee my dash air conditioner started blowing warm air. I assumed that some of my Duracool had leaked off possibly through the clutch seal. It haas been in for about 7 years now without any trouble.
Today I decided to recharge the system. However my gauges say that I am right on with the amount of Duracool.
And yet, I am getting no cool. I opened the high pressure side of the gauge so that some of it would bleed over to the low pressure line and bypass the expansion valve. Immediately the low pressure line frosted up but as soon as I shut off the flow from the high pressure side it warmed up again.
My diagnosis is that the expansion valve has gone bad. Before I tear into the heater box to get at it does anyone else concur or have a different diagnosis?
Emery Stora
77 Kingsley
Frederick, CO
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| Re: [GMCnet] dash air conditioner expansion valve [message #216456 is a reply to message #216443] |
Wed, 31 July 2013 20:56  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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If I remember correctly you have 2 evaporators in parallel? If that is the case is one blowing cold and one blowing warm? If so the warm one could have an expansion valve problem . If they are both blowing warm the add on could have a bad valve and the stock one would be cooling and a heat damper is partly open. If you only have the stock evaporator a heat damper is probably partly open I can't see how an expansion valve can be plugged with a normal suction pressure unless 2 evaporators are in the system. Normally a plugged expansion valve will cause the suction pressure to go into a vacuum unless there are 2 evaporators in parallel. In this case one will be operating normaly and the restricted one will ice up or do nothing depending on how restricted it is.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] dash air conditioner expansion valve [message #216500 is a reply to message #216443] |
Thu, 01 August 2013 07:56 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| emerystora wrote on Wed, 31 July 2013 20:31 |
On my way home from Shawnee my dash air conditioner started blowing warm air. I assumed that some of my Duracool had leaked off possibly through the clutch seal. It has been in for about 7 years now without any trouble.
Today I decided to recharge the system. However my gauges say that I am right on with the amount of Duracool.
And yet, I am getting no cool. I opened the high pressure side of the gauge so that some of it would bleed over to the low pressure line and bypass the expansion valve. Immediately the low pressure line frosted up but as soon as I shut off the flow from the high pressure side it warmed up again.
My diagnosis is that the expansion valve has gone bad. Before I tear into the heater box to get at it does anyone else concur or have a different diagnosis?
Emery Stora
77 Kingsley
Frederick, CO
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Emery,
I am having a little trouble figuring out how this can happen and match what you are describing.
If you have a 25psi suction side and 100 psi head pressure with the pump running and no cooling from either evaporator, something is radically wrong.
If the TEV were blocked up (why do you think they put them on flares), then the low side should be way low.
The fact that the condenser is only 100 indicates that there is just no heat being pumped. That fits. But, that can only happen if the pump isn't pumping.....
Still cooking on this. I'll let you know is something gets to come out right.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] dash air conditioner expansion valve [message #216547 is a reply to message #216443] |
Thu, 01 August 2013 15:40 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Not sure how Duracool numbers look with low charge but if that were R12 it would need a classic topping off at 100 high side. Why not add Duracool and see if that gets the cooling and numbers up. Seems easiest first step. Add to that 2 evaporators and I would think you would need to see higher numbers for 'work' to be done. .
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] dash air conditioner expansion valve [message #216685 is a reply to message #216488] |
Fri, 02 August 2013 16:37 |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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I'm interested to hear the impression of the new compressor.
Larry Davick
On Jul 31, 2013, at 10:47 PM, roy@gmcnet.org wrote:
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> A low high side pressure with 25 pound suction could indicate a compressor problem like bad valves? If it isn't pumping it won't cool worth a damn.
> --
> Roy Keen
> Minden,NV
> 76 X Glenbrook
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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