2004 SR5 4WD A/C Diagnosis

mmastera

New Member
May 1, 2020
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Could use some help - I am a complete beginner when it comes to the A/C system... This is a dual A/C vehicle.

The issue is not enough cooling. ie when on Max cool either with or without the rear A/C on, the vents blow between 50-60 degrees (usually in the 55-60 range). This is true for all vents including the ones in the rear. I've been doing my homework and bought a manifold gauge set, here are my findings:

Ambient temp while testing was about 87-90 degrees. I connected gauges, started the engine and turned A/C on max (temp control all the way to cold) and turned on rear A/C and set to 65 degrees.

Low side: 40 psi
High Side: 210 psi

I was expecting low pressures and intended to hunt for a leak but based on the above I believe the charge may be good? I don't have any experience reading a sight glass but what I witnessed was white whispy movement through the glass. I wouldn't say that I saw actual bubbles, but maybe that's what I was seeing when I describe "whispy" and it should otherwise be solid white? I took video of the sight glass, can't include in post b/c I'm too new. Will PM a link to the video if anyone cares to see it...

The FSM mentions running the engine at 1500 rpm for at least 5 minutes when testing, so I did that and didn't notice a change in the pressures. Possibly a slight improvement in cooling (still above 50). I have noticed that cooling does sometimes improve at higher rpms, but nothing to write home about, still above 50.

FWIW, the electric condenser fan did not come on during this testing although I am positive I've seen it in action previously. I'm assuming it just never got hot enough during the test for it to kick on.

Finally I looked into the heater control valve under the hood on the firewall near the brake booster. It was suggested that I check to make sure when the dial is turned to Max cool that the cable actuates the lever all the way to it's stop (it does). That being said, I noticed that the hoses on both sides of the valve are hot. Maybe I don't understand correctly but in the full cool position, shouldn't the valve close to prevent hot coolant from passing through? Shouldn't the hose leaving the valve going into the heater core be far less hot?

That's all I've done for now, looking for some guidance to help me take next steps...

Thanks!
 

Jgrauman

Active Member
Feb 18, 2019
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The blend doors are probably your issue. There is one one each Side. They control the output temp of the air. This door opens and closes depending on the temp you choose. A lot of the times the doors will develop a dead spot on the contact plate and the door won't slide past or gets stuck on a certain temperature. Currently my passenger side gets stuck on 72 and will click obnoxiously until I slide it to at least 75.
 

mmastera

New Member
May 1, 2020
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The blend doors are probably your issue. There is one one each Side. They control the output temp of the air. This door opens and closes depending on the temp you choose. A lot of the times the doors will develop a dead spot on the contact plate and the door won't slide past or gets stuck on a certain temperature. Currently my passenger side gets stuck on 72 and will click obnoxiously until I slide it to at least 75.
Much appreciated. I will look into this!
 

mmastera

New Member
May 1, 2020
6
1
3
45
The blend doors are probably your issue. There is one one each Side. They control the output temp of the air. This door opens and closes depending on the temp you choose. A lot of the times the doors will develop a dead spot on the contact plate and the door won't slide past or gets stuck on a certain temperature. Currently my passenger side gets stuck on 72 and will click obnoxiously until I slide it to at least 75.
Still looking into this. I found two doors passenger side. One appears to be the blend door (air servo actuator) and appears to be working. The other seems to just route air to the proper vents depending on which mode is chosen.

I looked and didn't see one on the driver's side. Does it matter that I have an SR5 and don't have dual zone climate controls?
 

Jgrauman

Active Member
Feb 18, 2019
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Yes, only have 2 for dual climate. So as you adjust the temp it is moving with each level of adjustment?
 

mmastera

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May 1, 2020
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Yes, only have 2 for dual climate. So as you adjust the temp it is moving with each level of adjustment?
I'll admit that I didn't check for each level of adjustment since I was focused on A/C blowing cold, only checked at Max Cool. I unscrewed the blend servo so I could hold it and watch and saw it move through it's full travel from all the way hot to all the way cold.
 
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Jgrauman

Active Member
Feb 18, 2019
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Only other thing I can think of is your heater control valve is corroded through. Pull hoses on it and verify it does indeed close
 

mmastera

New Member
May 1, 2020
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Only other thing I can think of is your heater control valve is corroded through. Pull hoses on it and verify it does indeed close
I'll do that. I did attempt to clamp it as a test but wasn't using the proper clamp and not sure how effective it was. I'll also revisit the pressures in case it's actually overcharged.


Thanks again for your help