Keeping interior cool

hekg said:

So it is possible to use a VOT Variable orifice tube in these trucks with rear AC? Mine is a 99 Tahoe with rear AC (C69) and I was looking into a variable OT but everything out there says for non-rear ac, i believe the designation is C60 trucks.

Is your truck a Tahoe as well? If it has worked out well for you, which brand and model number orifice tube did you buy?

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That setup is in my Express van. The Tahoe will also be getting a variable orifice when I dump the 8.1 back into it.

I though the rear ac in the tahoes and suburban used expansion valve and front used orfice tube.

95burban said:

I though the rear ac in the tahoes and suburban used expansion valve and front used orfice tube.

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They do as does my van. The variable orifice goes up front. Some say they do not work with dual ac but mine has been working great.

L31MaxExpress said:

They do as does my van. The variable orifice goes up front. Some say they do not work with dual ac but mine has been working great.

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I think you've mentioned in another thread, somewhere, but...

What's the p/n for the variable orifice tube you're using?

L31MaxExpress said:

That setup is in my Express van. The Tahoe will also be getting a variable orifice when I dump the 8.1 back into it.

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You're the only one that I've found so far that's been using this setup. Not sure why every variable orifice tube maker says that it is only for non-rear ac trucks. I don't really see what the problem would be but I'm glad I found your post.
I think I'll throw in a VOT as well. The Santech MT0625 one is only $20. Thnx!
Enjoy that 8.1 bad boy!

hekg said:

You're the only one that I've found so far that's been using this setup. Not sure why every variable orifice tube maker says that it is only for non-rear ac trucks. I don't really see what the problem would be but I'm glad I found your post.
I think I'll throw in a VOT as well. The Santech MT0625 one is only $20. Thnx!
Enjoy that 8.1 bad boy!

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I had a few other things to order on Rockauto and got mine for $7.

Its funny to me that the manufacturer used to have the results posted on a link on the AC forum I used to read and post on alot for a GMT400 Suburban with rear air in Phoenix.

L31MaxExpress said:

I had a few other things to order on Rockauto and got mine for $7.

Its funny to me that the manufacturer used to have the results posted on a link on the AC forum I used to read and post on alot for a GMT400 Suburban with rear air in Phoenix.

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Ok cool and you haven't noticed any decreased ac cooling during highway speeds?

hekg said:

Ok cool and you haven't noticed any decreased ac cooling during highway speeds?

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It cools better than ever with the parallel flow condenser and Sanden 4261.

If I felt like re-engineering the system, it would have the stock front condenser for the front evaporator. I would remove the stock rear feed line to the rear evaporator. I would mount a limo/bus style remote condenser under the the van with dual fans. I would tee off the compressor discharge hose and split the flow into the condensers. This is exactly what my old G20 van is getting when I add rear air back on it. The condenser is the weak link on a factory dual air system. An aftermarket parallel flow stacked in front of the stock condenser might also be doable. I will be retrofitting my old G20 to an expansion valve when I redo the system next year.

In the spring of ‘92 I bought a LD K2500 ECSB with the 5.7 and NV3500 and 9k on the odometer ( it was the dealer’s personal/demo truck). In June during the first heat wave of the season I was in town doing errands and making numerous stops. It seemed like it was taking forever to cool the cab down between stops. I stopped in at a friends shop to see if he could take a gander at it. He reached in to his toolbox and handed me an A/C thermometer and said “stick it in the center vent and run the A/C on max, should be 40-44 degrees.
After driving around for 15 minutes the thermometer read 42 degrees.

I think the design of the GMT 400 dash and ducts lend themselves to getting really hot in the sun, and it takes them a while to cool down, and on a hot, sun beating down kind of day, the A/C is working to cool the dash and duct work in addition to the cabin.

The heaters in my 96 and 97 K1500’s will give a guy heatstroke in 20 below weather.

My 96 and 02 Express/Savana vans A/C will give a guy an ice cream headache, but the heaters suck……..