88-94 5.7 Suburban A/C Diagnosis and Tuning

1998_K1500_Sub

Nitro Junkie
Joined
Jan 28, 2019
Messages
1,383
Reaction score
1,757
Location
Illinois
So, flush and go back with only 8oz of PAG 150.

No, you want 11oz of oil or thereabouts in your system. @PlayingWithTBI mentioned 8oz of oil for a single (not dual) evaporator system.

IIRC @L31MaxExpress is using 11oz (or nearly 11oz) in his dual-AC system.

You need not (re)flush your (recently flushed) system to swap to R152a. The PAG oil you recently installed will suffice.
 
Last edited:

Sawlty

OBS Enthusiast
Joined
Jul 16, 2022
Messages
63
Reaction score
50
Location
Texas
So, according to the shop manual, my temps and pressures are all that far off. I think I am slightly overcharged. Sure was hoping for some of that 40 degrees at the vent.


You must be registered for see images attach
 

Sawlty

OBS Enthusiast
Joined
Jul 16, 2022
Messages
63
Reaction score
50
Location
Texas
Any thoughts on the variable orifice tune that rock auto recommends for a 94?

Description says used for issues related to poor AC performance at idle.
 

Attachments

  • C14A59E3-9225-4B63-83C8-4109CFE9AD90.png
    C14A59E3-9225-4B63-83C8-4109CFE9AD90.png
    556.1 KB · Views: 3

1998_K1500_Sub

Nitro Junkie
Joined
Jan 28, 2019
Messages
1,383
Reaction score
1,757
Location
Illinois
Any thoughts on the variable orifice tune that rock auto recommends for a 94?

Description says used for issues related to poor AC performance at idle.

@L31MaxExpress and others discussed this recently (2-3wks), if I could only find that thread…

Do this: Use "Search" (upper-right corner), look for "variable" with @L31MaxExpress as the member.
 
Last edited:

L31MaxExpress

I'm Awesome
Joined
Apr 21, 2018
Messages
2,854
Reaction score
2,314
Location
DFW, TX
Any thoughts on the variable orifice tune that rock auto recommends for a 94?

Description says used for issues related to poor AC performance at idle.
The Four Seasons and AC Delco are the exact same piece. AC Delco does not build much of anything now, just slaps someone elses stuff in their box. I used the under 105°F version. The over 105°F version is meant for hot, dry climates like Arizona and the like.
 

Sawlty

OBS Enthusiast
Joined
Jul 16, 2022
Messages
63
Reaction score
50
Location
Texas
The Four Seasons and AC Delco are the exact same piece. AC Delco does not build much of anything now, just slaps someone elses stuff in their box. I used the under 105°F version. The over 105°F version is meant for hot, dry climates like Arizona and the like.
Any noticeable difference between the variable and non-variable?

I’ll search for the earlier thread.

Thanks.
 

L31MaxExpress

I'm Awesome
Joined
Apr 21, 2018
Messages
2,854
Reaction score
2,314
Location
DFW, TX
Any noticeable difference between the variable and non-variable?

I’ll search for the earlier thread.

Thanks.
I wish I had a direct comparison between. I put mine in with the AC rebuild. I previously had a Valeo upgraded HT6 replacement and a clean stock condenser with a Ford Red 0.062 orifice tube. My ac was cooling well but the compressor that had been in use since 2006 had a knock for the last 2 seasons it ran. AC rebuild was part of the plan all along with the 383 swap. It is definately cooling better now than it ever has and it worked extremely well before. The 0.071 to 0.062" orifice swap dropped my ac temps ~5°F at idle and that was measured before and after in the same system. It cooled the same on the highway after the orifice swap as well. Four Seasons 38887 is a 0.062 "condenser mounted" orifice for a dual air GMT400 SUV but it sits in the line near the inner fender liner. The variable orifice could break tomorrow, but so far it is working extremely well in the system.
 
Top