A/C Issues H2 2003
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Junior Member
Joined: Sep 2019
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A/C Issues H2 2003
My pressures are correct, high side and low side. The temperature out of the vent is in the 70's and I cannot get it to drop. It ocassionally drops into the 60's when I drive on the highway for awhile. Any help would be appreciated
Senior Member
Joined: Apr 2010
Posts: 1,006
From: Deep South Louisiana
Your suction pressure is a bit high (not normal), The 2003 did not have rear AC if I remember correctly so there would not be an expansion valve in the system just an orifice tube. Where these pressure taken with the truck idling and AC on MAX cooling, recirculate and fan on high with doors closed?
With your hand feel the suction line at the firewall and see if its COLD, it should also be sweating,
I would stop the flow of hot engine coolant to the heater core (clamp inlet hose) and see if the vent temps cool down, if so you have a temp mixture door issue, control module issue or even possibly a temp sender in the duct work failed. The H2 had AUTO AC so it has separate temp controls for both the drive and passenger so it would be a stretch to have both temp senders or mixture doors fail at the same time.
If the temp mixture door is not the issue I would pull the orifice tube and see if there is any debris from the compressor starting to plug it.
275 psi is a little high but not our of the realm for 95*, take a look at the engine driven clutch to make sure its ok, the fact that is does it on the hwy also indicates the fan clutch is not the culprit.
Its a little hard to diagnose AC issues over the net but the above are starting points I would look at first.
Neal
With your hand feel the suction line at the firewall and see if its COLD, it should also be sweating,
I would stop the flow of hot engine coolant to the heater core (clamp inlet hose) and see if the vent temps cool down, if so you have a temp mixture door issue, control module issue or even possibly a temp sender in the duct work failed. The H2 had AUTO AC so it has separate temp controls for both the drive and passenger so it would be a stretch to have both temp senders or mixture doors fail at the same time.
If the temp mixture door is not the issue I would pull the orifice tube and see if there is any debris from the compressor starting to plug it.
275 psi is a little high but not our of the realm for 95*, take a look at the engine driven clutch to make sure its ok, the fact that is does it on the hwy also indicates the fan clutch is not the culprit.
Its a little hard to diagnose AC issues over the net but the above are starting points I would look at first.
Neal
Last edited by legerwn; Sep 13, 2019 at 10:17 AM.
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Junior Member
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I replaced the oriface tube yesterday, but symptoms still the same. The suction line at the firewall is cold, but not sweating. I did close off heater core, and no appreciable change. I am an hvac tech in real life so this thing has me stumped. It's so much work to actually get to the evap, but I suspect if I could look at it, I would be better able to diagnose it.
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Joined: Jan 2017
Posts: 2,320
From: SC
You can add a cabin air filter if you really wanted to. Once done you can then physically see the evap core. The airbox where the core is under the dash is identical to the one on the GM trucks and from 1999-2002 they had a cabin air filter. In 2003 they decided to do away with that but the airbox still has where the cabin air filter cover can be installed. You just have to get the cover and a filter and then the opening just needs to be cut for it.
This youtube video shows it well.
GM docs for 99-02 trucks even show when looking for leaks with a detector or visually to remove the cabin air filter and look in there at the evap. I have not had time to but I plan on adding the filter to my H2 eventually. Nice to have a good charcoal filter to help eliminate odors, ect and a way to somewhat visually inspect the evap core if needed. Need to determine for sure which cover we need though. Looks like the L shaped one. There is also a straight version cover as well but I think that is for newer models.
This youtube video shows it well.
GM docs for 99-02 trucks even show when looking for leaks with a detector or visually to remove the cabin air filter and look in there at the evap. I have not had time to but I plan on adding the filter to my H2 eventually. Nice to have a good charcoal filter to help eliminate odors, ect and a way to somewhat visually inspect the evap core if needed. Need to determine for sure which cover we need though. Looks like the L shaped one. There is also a straight version cover as well but I think that is for newer models.
Senior Member
Joined: Apr 2010
Posts: 1,006
From: Deep South Louisiana
If I remember correctly the charge amount is 1.6 lbs, could be wrong as that is from memory. Is this the amount of 134a your charging to?
Next I would try setting the truck at around 1800 to 2000 rpms with a strong fan blowing into the front of the truck. Close the doors and set the AC to recirculate with it set to MAX cool, see if the vent temps come down any (need to see what the suction pressure does at these conditions). If the suction pressure comes down to anything close to 30 psi I would say the compressor is failing.
Was there any metal shavings/grey powder in the old orifice tube screen?
Neal
Next I would try setting the truck at around 1800 to 2000 rpms with a strong fan blowing into the front of the truck. Close the doors and set the AC to recirculate with it set to MAX cool, see if the vent temps come down any (need to see what the suction pressure does at these conditions). If the suction pressure comes down to anything close to 30 psi I would say the compressor is failing.
Was there any metal shavings/grey powder in the old orifice tube screen?
Neal
Senior Member
Joined: Feb 2015
Posts: 1,633
From: Birmingham (UK)
Agree with suggestions regarding debris etc and it is 1.6lbs of r134a for a 2005 (but check for 2003)
For my A/C overhaul I replaced the compressor, accumulator, orifice tube, and all the seals, and "reverse-flushed" (bought a kit) the evap-core and condenser. The video shows the debris found in just the pipes and was typical of everything else. The compressor and clutch were shot to bits, a real mess! In my limited experience I put the compressor failure down to my local garage over filling with r134a, everything was working before, but just no quite cool enough. Of course it took a while for the effects of over-filling to kill the compressor.
The condenser shipped to me accross the Atlantic was defective, hence I had to clean and re-usef the old one. Its important to "reverse-flush" as the mirco-bores trap small debris, I spent a long time on it untill the debris stopped coming out.
My point is you can quite easily reverse-flush the evap-core alone if you are concerned about it, personally I'd find any debris alarming.
For my A/C overhaul I replaced the compressor, accumulator, orifice tube, and all the seals, and "reverse-flushed" (bought a kit) the evap-core and condenser. The video shows the debris found in just the pipes and was typical of everything else. The compressor and clutch were shot to bits, a real mess! In my limited experience I put the compressor failure down to my local garage over filling with r134a, everything was working before, but just no quite cool enough. Of course it took a while for the effects of over-filling to kill the compressor.
The condenser shipped to me accross the Atlantic was defective, hence I had to clean and re-usef the old one. Its important to "reverse-flush" as the mirco-bores trap small debris, I spent a long time on it untill the debris stopped coming out.
My point is you can quite easily reverse-flush the evap-core alone if you are concerned about it, personally I'd find any debris alarming.
Last edited by oceanbrave; Sep 21, 2019 at 08:53 AM.