Vintage Air Gen V (5) or replace existing compressor, etc., for 1987 R20 Suburban?

Replace the Orfice Tube. Use the Variable model.
You can use 91% alcohol or Everclear to flush out the system.

Snoots said:

Replace the Orfice Tube. Use the Variable model.
You can use 91% alcohol or Everclear to flush out the system.

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I already replaced it, those were pics when I took the one that was in there out.

I’ll look into the alcohol for flushing, thanks.

There's enough gunk, I'd probably recommend swapping the Condenser if you aren't in a particular financial bind. If you open the system up again and want to play with orifice tubes, I don't have any experience with the variable orifice, you can also go with a blue or red orifice to get the system at a happier operating point with R134a, but I'll be honest, I'm not sure how the rear TXV will affect the system in any of those cases.
(I'm probably overthinking it, but in my days as an HVAC engineer for commercial applications, we never did any experimenting with multiple metering valves, but it is simple to say that two fixed orifices will have to be dead perfect to avoid starving one or the other, and two TXV's with wide adjustment ranges can easily 'fight' each other, which is why GM uses a TXV on the rear and a fixed on the front. The variable orifice up front probably doesn't have the adjustment to cause the fighting, and the blue or red tubes will probably allow the rear TXV to adjust same as before, but I don't have firsthand experience and just can't say for sure.)

Edit to add: If you decide to flush, make sure you flush the condenser backwards, especially if it is already a newer style with flat tubes. Evap should also be flushed backwards, unless of course you just decide to swap it along with the heater core when you do that. I have not done it on one of these trucks, but I would assume that doing one gets you most of the way towards doing both?

I had an aftermarket in dash A/C installed years ago on my '80 crew cab. Vents were in the OEM dash locations and used the factory heater. It could not keep up with the larger cab. I lived in Nor Cal at the time. Last year I helped a friend install a Vintage Air in his '62 Bel Air wagon. Front seat is good, but with no tinted windows, it gets warmer in the rear seat (now in middle Tennessee).

I have an early production '85 K30 454. My compressor was bad (A6) and the lines were bent. For me it was cheaper to get a Sanden Compressor with Vintage Air brackets, but the remainder is stock. I did read the plate version condensers are better for 134, so I added one of those. A/C with blows at 40*.

I have one of the later year (1989-1991) Suburbans that have the compressor on the passenger side of the engine and the alternator on the driver side. Will that prevent me from upgrading to a Sanden compressor? My system is factory but not doing well at all - the more I read the more I think I need to do a major rework (new condensor/dryer/orifice/compressor) and flush on the evaporators front+rear. I have the factory style (but probably aftermarket) smaller R4 compressor now (it might be an R6 I'm not sure how to tell but its the flatter one) - everyone seems to be indicating that the Sanden is better with 134 and I'd rather use common 134 than go to an unusual R12 replacement that can't be easily purchased in stores. I won't be doing anything this year (finally getting past A/C season here kind-of).

YakkoWarner said:

I have one of the later year (1989-1991) Suburbans that have the compressor on the passenger side of the engine and the alternator on the driver side. Will that prevent me from upgrading to a Sanden compressor? My system is factory but not doing well at all - the more I read the more I think I need to do a major rework (new condensor/dryer/orifice/compressor) and flush on the evaporators front+rear. I have the factory style (but probably aftermarket) smaller R4 compressor now (it might be an R6 I'm not sure how to tell but its the flatter one) - everyone seems to be indicating that the Sanden is better with 134 and I'd rather use common 134 than go to an unusual R12 replacement that can't be easily purchased in stores. I won't be doing anything this year (finally getting past A/C season here kind-of).

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Search the forums., there is a thread on this forum that I followed when I upgraded to a sanden with my 1990 burb. Let me know if you can't find it. It has part numbers for a compressor with the stock hoses, new serpentine belt, etc.

Snoots said:

Replace the Orfice Tube. Use the Variable model.
You can use 91% alcohol or Everclear to flush out the system.

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Everclear? That's my man!

SquareRoot said:

Everclear? That's my man!

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Other than flushing watermelon I think he mentioned it's only use.

Goldie Driver said:

Other than flushing watermelon I think he mentioned it's only use.

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Never underestimate the stupidity of a young Marine trying to establish his place in the pack. I immediately developed a lifelong respect for the poison.

SquareRoot said:

LS swap. It won't help the ac problem but it will make you not care about it any more.

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The real question, a new tensioner bracket for the AC compressor or a stretch fit belt?

Craig 85 said:

I had an aftermarket in dash A/C installed years ago on my '80 crew cab. Vents were in the OEM dash locations and used the factory heater. It could not keep up with the larger cab. I lived in Nor Cal at the time. Last year I helped a friend install a Vintage Air in his '62 Bel Air wagon. Front seat is good, but with no tinted windows, it gets warmer in the rear seat (now in middle Tennessee).

I have an early production '85 K30 454. My compressor was bad (A6) and the lines were bent. For me it was cheaper to get a Sanden Compressor with Vintage Air brackets, but the remainder is stock. I did read the plate version condensers are better for 134, so I added one of those. A/C with blows at 40*.

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that pusher fan your truck is lucky to be factory equipped with is probably doing your stock big block wonders when moving slowly and at stops. Does yours full-on with AC commanded on?


Do you have an AC heater core valve installed to redirect from the heater core so the ac isnt fighting that radiant heat added before it gets to you?

AuroraGirl said:

that pusher fan your truck is lucky to be factory equipped with is probably doing your stock big block wonders when moving slowly and at stops. Does yours full-on with AC commanded on?


Do you have an AC heater core valve installed to redirect from the heater core so the ac isnt fighting that radiant heat added before it gets to you?

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I actually added it. All my other 454 trucks had it. This truck didn’t have the Z82 tow package which included the aux fan. It was easy to add.

The fan is controlled by a temp sensor on the passenger head (OEM setup and parts). It’s basically a ground for the fan relay. It turns on/off at certain temps. It’s not connected to the A/C like most people think. Definitely helps temps in traffic and at idle.

My A/C guy adjusted the blend door, so I don’t have heat bleed from the heater core.

Craig 85 said:

I actually added it. All my other 454 trucks had it. This truck didn’t have the Z82 tow package which included the aux fan. It was easy to add.

The fan is controlled by a temp sensor on the passenger head (OEM setup and parts). It’s basically a ground for the fan relay. It turns on/off at certain temps. It’s not connected to the A/C like most people think. Definitely helps temps in traffic and at idle.

My A/C guy adjusted the blend door, so I don’t have heat bleed from the heater core.

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The heat bleed is still happening, albeit if you have the heater door blend door (fun fact, i think they sell them new still apparently they fall apart?) because there is still air leakage and the thing is radiating heat inside the box(better in a square than it would be in, say, a gmt800 or gmt400 which are going to be more in the cabin and a more insulated cabin at that)

The heater core , if you bypass the hoses with a valve thats hooked up, will not radiate the temp at all, and the temps are known to drop 15 degrees in the most extreme ones, expect less than 10 if your door is where it needs to be

You could modify your wiring to add another grounding event for the relay, i would, since low speed and idle that engine is at the disadvantage of the big block making heat already, and the AC will benefit the most simply because its got the air flow over the condensor. Unless youre using severe duty type clutch for the clutch fan (Icant tell if you have one or not)

Craig 85 said:

I actually added it. All my other 454 trucks had it. This truck didn’t have the Z82 tow package which included the aux fan. It was easy to add.

The fan is controlled by a temp sensor on the passenger head (OEM setup and parts). It’s basically a ground for the fan relay. It turns on/off at certain temps. It’s not connected to the A/C like most people think. Definitely helps temps in traffic and at idle.

My A/C guy adjusted the blend door, so I don’t have heat bleed from the heater core.

Click to expand...

My 454 truck has the same fan. It runs all the time as soon as the key is turned to ON. From this thread I’m guessing something isn’t right with that?

beady said:

My 454 truck has the same fan. It runs all the time as soon as the key is turned to ON. From this thread I’m guessing something isn’t right with that?

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The switch has failed or its been modified and once key on power hits, it grounds