88-94 5.7 Suburban A/C Diagnosis and Tuning

L31MaxExpress

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88F on the suction side? Why 88F, was the rear fan blowing on high?



Not the result I had hoped-for.


How does one know the R152 isn't impure, too?

Walmart's house brand of R134a is $8.88/12oz locally. I needed R134a in a pinch this weekend (I have multiple 30# cans at home) so I bought two. The result was very cold air on my S10.

Five cans of this would give you 60oz for about $50. Not as cheap as R152.



Very good.
I have tested what I get from Sam's multiple times. It is 97-98% pure R152a with 2-3% unidentifiable. It has an embitermint in it to prevent substance abuse. In the 6 years I ran it, no ill effects noticed when I rebuilt the system. I only rebuilt the system because I had it apart and it had a noisy compressor even before the R152a. R152a itself is mildly flameable but less flameable than R1234YF. The YF has lower ignition temps.
 

L31MaxExpress

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I had used it when I rebuilt my wife's 2002 Ford escape system 6 months ago. Hers cools better than mine, but not by much, with a average delta on the highway of 35. She drives much less so I have not had to deal with many complaints.

The rear fan was on high, yes.

My 134 will not ignite and extinguishes flame when it interacts.
Well that could be a good sign, but still have my doubts as to what it really is. Conterfeit refrigerant has been a big problem especially since the price spike. I like to know what I have.
 

L31MaxExpress

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FWIW my 110K mile system on my 2011 Pathfinder regularly hits 60°F deltas on the highway with the blowers both on high and that was with R134a. Around town in 105°F temps in the shade, it was getting down to 44°F at the vents after 20 minutes of driving. Given what I would consider subpar performance on two vehicles something seems off. The ambient temp sensor in good airflow driving around was showing 114°F when this was taken. 114 to 46 = 68°F between the ambient sensor and the thermometer in the vent. Even if the 105°F is used as a reference point 105-46 is 59°F.

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Wildblue19

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We need to rule out another variable, and the biggest one it seems now is the 132 as most suspect.

I may attempt obtaining 152 to dust off the truck this evening. Any brand preference? I am concerned about not being able to find a can piercer locally to assist in the 'cleaning' of my truck.
 

1998_K1500_Sub

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I may attempt obtaining 152 to dust off the truck this evening. Any brand preference? I am concerned about not being able to find a can piercer locally to assist in the 'cleaning' of my truck.

@L31MaxExpress, do you just use a typical "can tap"?

@Wildblue19, NAPA et al have can taps, but whether they're the proper size remains to be learned.

(edit) I posted just a moment too late.

I wonder what would happen if one used that tap on a can of Kraft Easy Cheese. Probably need to install a larger orifice tube. The price per oz is about the same as R134a at Walmart so it's a toss-up.
 

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L31MaxExpress

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We need to rule out another variable, and the biggest one it seems now is the 132 as most suspect.

I may attempt obtaining 152 to dust off the truck this evening. Any brand preference? I am concerned about not being able to find a can piercer locally to assist in the 'cleaning' of my truck.
For the most part you have eliminated my biggest suspects. Assuming you have pinched off the heater hose at the hot water outlet on the back of the engine.

What I get out of your testing.

Compressor is capable of pumping.
Rear expansion valve makes little difference pinching the high side line so it is not flowing excessively.
Front orifice tube is flowing given the high low side pressure readings and the fact it behave the same with a fairly clean stock orifice in place.
Also assuming you have done the condenser mist test to verify it is cooling adequately.
The charge has been altered up and down with no huge gains.
To me that leaves one variable, the refrigerant gas. In two completely different systems it is showing fairly suspect results.

The dusting should give us a controlled expirement. I would start with 30 oz monitoring pressures and temperarures and work up from there.
 

L31MaxExpress

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Thanks. I'll go take a ride over there now. For the conversion, is 40 oz sufficient?
No problem, will have to ask for it. It will be in the bulk murray ac parts in the back.

My van was a spec of 68oz on R134a. With what I could get out of 4 x 10oz cans it is ice cold. I too have a parallel flow and Sanden. Should be fairly equal systems in theory.
 

L31MaxExpress

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@L31MaxExpress, do you just use a typical "can tap"?

@Wildblue19, NAPA et al have can taps, but whether they're the proper size remains to be learned.

(edit) I posted just a moment too late.

I wonder what would happen if one used that tap on a can of Kraft Easy Cheese. Probably need to install a larger orifice tube. The price per oz is about the same as R134a at Walmart so it's a toss-up.
Orifice tube he has is what I am running and I used a Ford 0.062 prior.

Edit- Should say I have the same one for an evaporator mount.
 
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