97 Tahoe condenser recommendations

[n8in8or]

So AllData is not showing SUV's: just pickups. The factory sticker for R134a at 3lbs is gospel, period.

I looked up the part number for components for both the Tahoe withOUT rear air and a pickup. The evaporator, accumulator and compressor are all the same. The only component different is the condenser. Could the different condenser account for .75 or 1.0 more pounds of refrigerant? I wish I had a factory service manual....

 

[FellowTraveler]

I looked up the part number for components for both the Tahoe withOUT rear air and a pickup. The evaporator, accumulator and compressor are all the same. The only component different is the condenser. Could the different condenser account for .75 or 1.0 more pounds of refrigerant? I wish I had a factory service manual....

My 99 Suburban w/dual HVAC has a larger accumulator.

 

[n8in8or]

My 99 Suburban w/dual HVAC has a larger accumulator.

That makes sense to me. I don’t understand why the tag in mine is giving a larger capacity, yet it’s the same size.

BTW, I charged mine with 2.25 lbs and it’s blowing 42 degrees out of the vent.

 

[WarWagon]

You had it at 42 degrees with more than 3 lbs in it correct? Due to efficiency loss of liquid in accumulator an undercharged system actually is colder. Regardless my 1993 pickup takes 36 oz after the R12 conversation # are run.

All I can guess at is higher load takes more R134a. Unk why it would be same accumulator and evap.

Run it low and the oil stops moving getting trapped in the evaporator. Compressor fails and dusts system. The second I get colder air in patch I recharge it or it will lock up the compressor.

Put 3 lbs aka 48oz in it.

 

[Burning oil]

I think I have a real old post 2015ish when I did my system. The highlights were I used a 2011 iirc condenser from a F250/350 gasser. It maxed out the space available in the core support. Had to have custom fittings welded to it also. The other thing was I put the orifice tube in the eval.
Drove it today for first time in a long time and AC worked great actually got cold inside and it was a very hot muggy day today. Anyway my 2 cents.

 

[Burning oil]

Just found old thread. http://www.thetruckstop.us/forum/threads/slight-redesign-of-a-c-system.43197/

 

[n8in8or]

I added another can so now I have 3 pounds in it. We have some 90 degree weather coming up later so I’ll check the gauges then.

 

[THEFERMANATOR]

It has been so many years since i did a lot of a/c work, and I get into more stuff than my brain can remember so I don’t have THE answer, but...As some of our guys here are pro hvac guys, they might explain it better.

Automotive is the only place that does refrigerant and oil by only weight instead of difference in pressure high vs low, sub freeze, compressor amp draw, etc.

When a an a/c unit is done for a house for instance, there is a base charge by weight, then the gauges, amp probe, thermometer is used to get the exactly amount of refrigerant installed. For the oil, since hermetically sealed compressor is used, almost never is more oil added. But in automotive, if you drain the compressor and flush the system, you have no oil. You can then add the full amount.

Anyways, back when I was doin a/c in semis and trucks, i would charge to specified amount. Then tweak it and get as much a 5 degrees colder. More oil is safer for compressor, but less cooling. So I ran little
less oil, more r12 or r134a, and she wasmuch happier. But I also installed different spec pressure sensor to shut system down when any leak started to save the compressor.

I figured out the difference in a week, wrote it down and used it for a few years, then when I quit wrenching, chucked my notes. If a pro hvac guy could help out here, it could help your performance by explaining how much extra oil there is.

The answer is quite simple. With auto a/c the exact system size is a known factor, with home a/c it is a variable due to what size lines were used and the length's. So with auto a/c, you know the exact system size, so you charge it to the specified amount, if the oil charge is correct the pressures will be correct, and the low pressure cycling switch will open when evap temps reach roughly 35 degrees since temperature to pressure is in direct coorelation to each other when the system is filled to a specified capacity. I still remember when doing a/c repairs, charging the system to the specified charge, and then adding oil until it cooled properly. If your pressures were too high or it was really slow to cool, you knew it was overfilled with oil.

 

[1994ch]

I just replaced the AC system in my tahoe. Was at the junkyard getting the high and low pressure switches and all the tahoe and pickups I saw said 2 lbs on the sticker on the accumulator. I saw one tahoe that said 2 lbs for tahoe and 3 lbs for suburbans. So I charged mine to 2 lbs.