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Ac door operation and diag

obijuank5

obijuank5

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My factory service manual is leaving something to be desired.
Is there something out there that I can look at to corroborate my ac on the 90 burb? I screwed with everything and I’m second guessing my work.
I’m having issues and before I Hail Mary a compressor on it I want to be sure.

Is there a way to force it into recirculating mode all the time? And by that I mean block off the fresh air intake. I have already put a valve on the heater core but damn I swear I can’t get cold temps out of this thing.

The gauges are telling me weak compressor if I’m using this right. The high side is low.
DDE04982-1FBC-4EE1-92EC-3632B48D8879.jpeg
 
Max a/c position should be recirculate. How many ounces of 134 ya got in it?
Does it have rear air?
 
It is a rear air setup and this is my calculation for 134. It is also a sanden 508 conversion. I forgot to add that earlier.
I know my max ac interior recirculate door functions but I want to block off all exterior air getting in to be damn sure it’s not just the cowl flap. That design sucks imo but that’s not a big deal.

20A5868E-093D-4B26-988B-2D654B90CFF6.jpeg
 
Doesn’t the fresh air intake just travel from the cowl, down the passenger side and through the air vent at the passenger side kick panel? If so then just remove vacuum tube (and cap it off) from the actuator behind the plastic cover on the kick panel to prevent the door from opening.
 
I think I used about 8oz. of pag150 but I still have the R4 compressor. I think I also used around 70 oz. so you may need some more juice
 
JoshHefnerX said:
What ambient temp was that at?

That's the bottom end of about 80deg on the chart I ref.

View attachment 508547
Click to expand...

So I think it was about that area ambient temp and I did add a can to see what the pressures did then.
I believe when I did that the low side increased while the high sided stayed low.
 
3.8 seems high to me for a 134a conversion. Is the r12 sticker still there and legible ?

The 508 is the smaller of the 2 Sanden options, does adding eng Rpm effect the pressures?
If you do end up doing a new compressor get the 700 series, bigger displacement.
The temp door cable is adjustable behind glove box.
 
Man I need to take a break. I’m clearly in the wrong headspace to be putting attention here right now. Sorry if this is very unorganized.

It is a sd7h15 model 4711 which should be the larger one isn’t it?

I used the service manual for the r12 numbers because my sticker is not there. And that could still be way wrong.
 
Correct that is the bigger one.
Thise pressures really don't look that bad. Ambient is needed to be sure.

Did you get a regulator/vent temp?
Use a big box fan in front of condenser and see what happens
 
Which orifice tube are you using? With the smaller compressor and R134 swap, it should be smaller than the stock one. That affects the pressures.

Is the outlet of the evap cold?
 
Wes Harden said:
Correct that is the bigger one.
Thise pressures really don't look that bad. Ambient is needed to be sure.

Did you get a regulator/vent temp?
Use a big box fan in front of condenser and see what happens
Click to expand...

I did add a condenser fan to see if that was the issue. No change. The hd fan clutch that’s on there will pull my shirt up to the grille and keep it there no problem. I sealed up the space between the radiator and condenser and shroud.


Blue85 said:
Which orifice tube are you using? With the smaller compressor and R134 swap, it should be smaller than the stock one. That affects the pressures.

Is the outlet of the evap cold?
Click to expand...

The evap is cold to the touch on both sides. It is dripping like a mfer for sure, I just have no experience to say if it’s cold or ice cold. I can’t tell.

This is the orifice tube in it.
Notes said up to 105, that’s why I chose it. It could be the wrong one for sure.
966255A7-1746-4A24-B4ED-A546F70CD4A2.jpeg
 
Thats good air flow.

If the accumulator is cold you should have cold air in the cab. If you can't touch the evap inlet for long it's plenty cold. No IR gun ?
What is the rear air doing ?

I believe that orifice tube is the variable. It is supposed to work better at low speeds. I tried it in the 01 and now have a fixed. Not sure I gave it a fair shake before changing it.
 
The VOV is supposed to be more forgiving on sizing, so they only have a few part numbers. If the outlet of the evap is a similar temp to the inlet and the line is cold out to the compressor, the system is charged. Although with a dual A/C you would need to verify the same at the rear evap. Is that one running the original TxV?

Keep in mind that compared to the original A/C, you've moved to a worse refrigerant and a smaller compressor, so it won't cool like it was new. Did you change any other parts?
 
I abandoned the VoV a while back because they're easier to plug, but to fair, any tube will plug with much of anything floating around in there. Plus, A/C only matters like 30 days a year here.
 
obijuank5 said:
Is there a way to force it into recirculating mode all the time? And by that I mean block off the fresh air intake. I have already put a valve on the heater core but damn I swear I can’t get cold temps out of this thing.
Click to expand...
Have you verified that the blend door is properly sealing towards the cold side? The clip on that door is known to break and the seals go bad over time. It sounds like you've blocked coolant flow so you wouldn't get heat, but if the cabin air is partly/mostly through the heater core instead of the evap, you'll get very low cooling. It also will take most of the load off the A/C system, which will bring down the high side pressure, so it sounds like a plausible theory to me.

I suppose in that instance the rear A/C might work fine.
 
I had a vov and was not happy. Switched back to a white or blue, cant recall.
 
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