Keeping interior cool

[L31MaxExpress]

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……..

Heater in my 97 will cook you out even with a 170F thermostat. Just takes an old iron small block a while to warm up when it is 15°F on a cold country morning.

 

[hekg]

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

Awesome. I just ordered a CSF parallel condenser as well. GM calls for 64oz of refrigenrant and 11oz of pag oil for these Tahoes. Do I have to modify these numbers to work with the new parallel flow setup? Or is the 64oz/11oz perfect just the same as with the old serpentine condenser?

 

[L31MaxExpress]

Awesome. I just ordered a CSF parallel condenser as well. GM calls for 64oz of refrigenrant and 11oz of pag oil for these Tahoes. Do I have to modify these numbers to work with the new parallel flow setup? Or is the 64oz/11oz perfect just the same as with the old serpentine condenser?

Sorry missed your post. You will probably have to modify the numbers slightly. With R134a, start with 4 cans (12oz each) and creep up a couple ounces at a time. Stock thats 5.33 cans, but I have a feeling you will find it cooling best somewhere between 4-5 cans. The tubes in the parallel flow condenser are smaller and hold less gas but are designed to block less airflow and shed heat more easily.

I prefer to use a scale on vehicles I am not totally familiar with the operating pressures and temperatures on so that I know exactly how much is in the system. Also comes in handy later if you have to pull the system down and recharge. If your commute includes alot of slow speed driving and idling I would change the 0.071" White orifice either to a VOV or a Yellow 0.062. I have had great results with both the 0.062" tube and a VOV. The Tahoe uses the condenser mounted style orifice even though it is not mounted in the condenser when equipped with rear ac. A 1994 Cadillac Seville uses the condenser mounted yellow 0.062" orifice. I ran one in my 99 for several years. Cooled extremely well even at idle with R134a.

 

[yevgenievich]

I used Cadillac orange I believe on my 91 suburban. That along with parallel flow condenser, sanden and aux fan made for cold ac even in 43* C heat sitting idle in direct sunlight. Had the coolant bypass as well.
Stock 97 system in burban does not cool as well

 

[caw_86]

Even the ones GM put on do not fully close. I put a manual ball valve on mine. It is closed about 9 months out of the year here.

If your ac is not working well it is not the era of truck. I have been in a family of this generation of trucks, suvs and vans since they were new. My uncle had a 97 ECSB and my aunt had a 98 Yukon that they had since they were new back in the day, long since sold them. The 97 Express has been around since 98. My brother and I have had no less than 7 Tahoes, Yukons, Suburbans and Trucks. The 99 Suburban and 99 Tahoe we kept for several years would both freeze you out of them. If the ac is not cold it most likely has a leak or airflow across the condenser issue. If the ac is blowing weak the evaporator is clogged with crap or the blower motor is weak. The foam seals at the duct work also degrade over time and leak the air out behind the dash. Wrap the joints in the ducts with aluminum tape. My van and Tahoe will both blow your hat off with cold air.

The ball valve is a great idea, especially for texas weather. My previous owner deleted the vacuum valve in mine, a manual valve that i know is closed seems like the way to go. Mind sharing a picture of what it looks like installed

 

[cjcb1100]

I just did a sanden s7h15 and a parallel flow and all new parts evaporator condenser lines dryer etc everything new, i also replaced the foam on the blend door and i know their working correctly. getting 60 deg at idle and 49 or so at freeway. I did vac system for 1 hour and my pressures are @ 101 out side of 52 and 230 or so according to the charts my high side is low should i go with a smaller orifice ? I have the oem .072 in it now or get a vov mine is in the evaporator atm thanks for any info and help

 

[L31MaxExpress]

I just did a sanden s7h15 and a parallel flow and all new parts evaporator condenser lines dryer etc everything new, i also replaced the foam on the blend door and i know their working correctly. getting 60 deg at idle and 49 or so at freeway. I did vac system for 1 hour and my pressures are @ 101 out side of 52 and 230 or so according to the charts my high side is low should i go with a smaller orifice ? I have the oem .072 in it now or get a vov mine is in the evaporator atm thanks for any info and help

I have a VOV in the van. After a year it is still working great. Some reviewers claim they have failed on them. YMMV.

If you want to try a smaller fixed orifice grab a Ford Red 0.062. I have had fairly good, consistent results with the Red Ford tube.

At low vehicle speeds and idle I find the Orange tube has an edge over the Red one, but the compressor will cycle more frequently at highway speeds.

 

[cjcb1100]

mine is a 90 and i dont have the high side switch yet need to install also i am runing two aux fans in the front to try and help do you know witch vov you have id like to try one

 

[cjcb1100]

I found a red one on ebay for a buck so its ordered

 

[L31MaxExpress]

mine is a 90 and i dont have the high side switch yet need to install also i am runing two aux fans in the front to try and help do you know witch vov you have id like to try one

I just noticed that you have a 1990. Which model is it? Where is the orifice tube in your 1990? If it is condenser mounted, you need the Yellow/White GM condenser mounted tube. Same orifice size as the Red Ford, but intended for a condenser mount.