Dual AC systems

[rrmd]

I've installed a front and rear a/c unit in an old, 6 cyl. limousine that never had ac before. I configured it as I found info in the ariazone AC manual. I'll try to post a photo of the system. There are 2 cut off switches installed so that there could be front or rear...or both ac evaporators working at the same time. I have a problem, however. It seems that when just the front is activated, occasionally the compressor clutch toggles on and off in rapid succession. When the rear is activated, it stops and everything is normally good and cold.

[rrmd]

img016 (4) X.jpg (236.07 KiB) Viewed 2217 times

[tbirdtbird]

"ariazone AC manual"
I do not know what that is.
Two TXVs in a dual system? Usually an OT and a TXV.

We need more data...
Hi and low at 1500 RPM with front only activated, again with rear only activated, again with both activated.
What brand compressor?
What are vent temps front and rear depending on what is activated
How did you charge it? IE weight of refrigerant installed? Surely there was no spec to follow. Pressures may tell us if it is undercharged. How much oil?
We assume R134
Is R/D installed in the correct direction?

[rrmd]

I don't have that data presently. I am more worried about total 134a wt. I just looked on a mid-90' Suburban (1500) with rear air and the chart shows 64 ozs. Does that sound plausible? I picked that model because of the length of the vehicle and distance between front and rear evaporators.

[rrmd]

BTW it is a Classic Auto Air system.

[tbirdtbird]

"I don't have that data presently. "
Why not? Is it possible that you setup your system and charged it somehow without a manifold gauge set? (MGS)
Not much we can do without it.
There is a current thread on here about Suburbans with front and rear air and problems that arouse from not removing the OT that came installed in the condenser outlet. I'd check that thread and wonder if you have a similar problem

[tbirdtbird]

https://autoacforum.com/viewtopic.php?t=14819