Keeping interior cool

[cjcb1100]

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.

I swapped everything to the 95 model parts its a 90 k2500 LD, but all the ac except the pump 95 r134a parts and originally it was in the condenser now i have it in the evaporator

 

[L31MaxExpress]

I swapped everything to the 95 model parts its a 90 k2500 LD, but all the ac except the pump 95 r134a parts and originally it was in the condenser now i have it in the evaporator

Ok good deal, just wanted to make sure you avoided that mix-up prior to opening the system. It has caught me without the right orifice tube a few times. I know keep a few of each in my tool box "junk" drawer.

 

[cjcb1100]

Ok good deal, just wanted to make sure you avoided that mix-up prior to opening the system. It has caught me without the right orifice tube a few times. I know keep a few of each in my tool box "junk" drawer.

I have a few but not red mostly black and white i used my last blue one a while back

 

[hekg]

I just realized that the shop that fixed my ac a long time ago put the orifice tube on the condenser outlet right behind one of the headlights like on the pickup trucks, but my Tahoe is a C69 with rear air.
Should the orifice tube be right before the evaporator line instead? Would this be the cause of all of my weak front ac issues?

 

[L31MaxExpress]

I just realized that the shop that fixed my ac a long time ago put the orifice tube on the condenser outlet right behind one of the headlights like on the pickup trucks, but my Tahoe is a C69 with rear air.
Should the orifice tube be right before the evaporator line instead? Would this be the cause of all of my weak front ac issues?

That would cause both units to have poor performance, since all the refrigerant is then metered through a hole designed to feed the front evaporator alone. The orifice goes after the tee, in the fitting between the front evaporator and the tee.

It still amazes me that mechanics screw that up on the Suburbans and Tahoes. They add an orifice tube there for what reason? I hope there is some condenser brand that comes with one already installed there. It would atleast make sense that they simply missed the fact it was there rather than ignorantly adding one.

 

[hekg]

Ok I guess i'm having the system evacuated again this weekend so that I can move the OT to the correct location or rather now replace it with the variable OT that you recommended.

Today I suddenly remembered that when I had my ac fixed that time and went to pick up my truck only the front air was cooling. I told the mechanic and he said that he didn't know because I hadn't mentioned that it had rear air. Guess it was my fault for trusting him!

So I had to leave the truck and come back the next day and now the rear air was cooling. I bet that since he didn't know that it had rear air, he just installed the orifice tube after the condenser like on any other C1500 pickup.

I have been driving my truck like this for around 10 years with very weak and disappointing front air ... I have to laugh

 

[L31MaxExpress]

Ok I guess i'm having the system evacuated again this weekend so that I can move the OT to the correct location or rather now replace it with the variable OT that you recommended.

Today I suddenly remembered that when I had my ac fixed that time and went to pick up my truck only the front air was cooling. I told the mechanic and he said that he didn't know because I hadn't mentioned that it had rear air. Guess it was my fault for trusting him!

So I had to leave the truck and come back the next day and now the rear air was cooling. I bet that since he didn't know that it had rear air, he just installed the orifice tube after the condenser like on any other C1500 pickup.

I have been driving my truck like this for around 10 years with very weak and disappointing front air ... I have to laugh

I would skip the variable if you have not already sourced it. Mine ended up sticking closed intermittently at times after a year of use. Worked good while it worked, then failed.

 

[hekg]

I would skip the variable if you have not already sourced it. Mine ended up sticking closed intermittently at times after a year of use. Worked good while it worked, then failed.

Aww man that's too bad .. I'm canceling that order in that case. Thanks for the heads-up.

I'm actually really looking forward to working on it again this weekend and seeing if I finally get the really cold air that everyone else talks about by moving the OT. The best I ever got was 68 degrees in the front.
I will report back with my results

 

[hekg]

I took apart the condenser outlet tube and removed the orifice tube that was there and when I took apart the other orifice tube location fitting I found that there was already another orifice tube in it, so I've been driving around for years with two orifice tubes in the front and the expansion valve in the rear.

I vacuumed the system down for an hour and added 60 oz of refrigerant but the coldest temperature that I was able to get out of the vents was 54 degrees even while driving down the highway at 80mph.

Since these Tahoes with rear air normally take 64oz of refrigerant and I only added 60oz, is it actually possible that those missing 4 ounces are keeping me from getting the vent temps down into at least the 40s? I've seen others on youtube with theses same trucks get the vent temps down to 37 degrees so I'm still way off at 54.

 

[L31MaxExpress]

4oz is not enough to create that much of a difference in cooling. My best guess is it is either an airflow issue with air not going through the evaporator coil to be cooled or the compressor is short cycling. I have seen the cycling switches for these trucks defective right out of the box. My Van and Tahoe both cooled into the 30s at highway speeds even with the OE AC systems.

Sounds like removing that extra orifice tube made a big difference.

Have you removed the blower motor and inspected the evaporator coil? They get jammed up with debris and airflow starts being forced around the core. I have cleaned the core and used aluminum duct tape to seal the gaps between the evaporator coil and plastic housing on several occasions.

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