New compressor - A/C Not functioning

[Josh]

Hey guys, looking for some help with my A/C system.

My car has a LS4 V8 and the A/C has always given me trouble.

The A/C system was all replaced 2 years ago.
-New lines from DPI (Eaton EZ clip)
-New 134a condenser from DMC
-New evaporator, dryer, and orifice tube from Special T

I was also using the stock LS4 A/C compressor, which gave me sub-par cooling due to the fact it is a variable displacement unit, which was unknown to me when I originally installed it.
I switched it out to a Sanden sd7h15 compressor, the same that is used as a replacement in the stock delorean. The only difference for my application is it has a 7-rib pulley and a different back plate.
Link to the new compressor: https://www.summitracing.com/int/par...-vma/overview/
My thinking was that I now have an all stock system, so it should cool as well as stock.

However after charging it up yesterday the A/C is worse. It is pretty much non existent in terms of temperature.
The compressor clutch still engages, so the wiring is not an issue.

Any ideas?

[FABombjoy]

That compressor should be lovely - I have the 4708C clone. What do your manifold gauges read?

[Nicholas R]

Hey guys, looking for some help with my A/C system.

My car has a LS4 V8 and the A/C has always given me trouble.

The A/C system was all replaced 2 years ago.
-New lines from DPI (Eaton EZ clip)
-New 134a condenser from DMC
-New evaporator, dryer, and orifice tube from Special T

I was also using the stock LS4 A/C compressor, which gave me sub-par cooling due to the fact it is a variable displacement unit, which was unknown to me when I originally installed it.
I switched it out to a Sanden sd7h15 compressor, the same that is used as a replacement in the stock delorean. The only difference for my application is it has a 7-rib pulley and a different back plate.
Link to the new compressor: https://www.summitracing.com/int/par...-vma/overview/
My thinking was that I now have an all stock system, so it should cool as well as stock.

However after charging it up yesterday the A/C is worse. It is pretty much non existent in terms of temperature.
The compressor clutch still engages, so the wiring is not an issue.

Any ideas?

My understanding is that you can make the variable compressors fixed by modifying the refrigerant control valve. I never gave much though to this though. I'm not sure I understand why the variable displacement is worse.
RCV Valve Modification.PDF

This is odd though that you're not getting any cooling at all. Even last week when I was running with my trashed compressor, I was getting ~55° air from the vents. You're sure you put the orifice tube in the correct direction right? Do you still have the heater fluid shutoff valve active? I always notice a difference between "Normal" and "Max" AC in my car primarily due to the heater not circulating fluid during "Max".

[Josh]

That compressor should be lovely - I have the 4708C clone. What do your manifold gauges read?

At idle (650rpm)

Low side - 32psi
High side - 150psi

Ambient temp was about 80F
Charged with 2.2lbs 134a

[Josh]

My understanding is that you can make the variable compressors fixed by modifying the refrigerant control valve. I never gave much though to this though. I'm not sure I understand why the variable displacement is worse.
RCV Valve Modification.PDF

I never even knew this was a thing. This may be a back up plan. Thanks Nick!

[Delorean Industries]

At idle (650rpm)

Low side - 32psi
High side - 150psi

Ambient temp was about 80F
Charged with 2.2lbs 134a

Too much refrigerant in the system. You need to back the refrigerant down to 24oz with your configuration (two cans) This is from taking into account the parts list supplied above.

[Josh]

Too much refrigerant in the system. You need to back the refrigerant down to 24oz with your configuration (two cans) This is from taking into account the parts list supplied above.

After running your crazy yankee numbers through the computer, that is only 1.6lbs? Why so little. I will certainly try it however I am curious. It would make sense that the system is overcharged, however the pressures seem OK to me too.

[FABombjoy]

Low side - 32psi
High side - 150psi

Too much refrigerant in the system. You need to back the refrigerant down to 24oz with your configuration (two cans) This is from taking into account the parts list supplied above.

Those readings seem low for 80F, though. Assuming system was fully vacuumed, could charge measurement be inaccurate?

[Josh]

Those readings seem low for 80F, though. Assuming system was fully vacuumed, could charge measurement be inaccurate?

That's what i was thinking, but i will try anything at this point! So all recommendations are welcome.

System was under vacuum for about 2hrs, it should be good. Another issue may be that i replaced the compressor only, not the orifice tube and dryer. I figured since I was removing a good working compressor it was fine to retain the current parts.

The gauges could potentially be of issue, they are cheap ones from HF.

[Bitsyncmaster]

Those readings seem low for 80F, though. Assuming system was fully vacuumed, could charge measurement be inaccurate?

+1

But since your idle is only 650 RPM that could account for lower high side pressure at idle.