All new a/c parts but still not cold

Hi I have a 99 suburban LT k1500 with rear air/heat. 186xxx miles. I had a belly leak on my compressor so I decided to replace pretty much everything up front. I replaced the compressor, condenser, dryer, orfice tube, evap core and the manifold lines and all parts are acdelco. I flushed the couple of hard lines I didn't replace in the front. I didn't touch the rear at all. I used new pag150 and replaced any o rings that I touched other than the new ones that came on the new parts.

I do body work for a living so I am very familiar with a hvac machine and how to correctly use one. Although I'm no expert on diagnosing ac problems. I ran a vacuum for 1 hr just to be safe. And charged it to 3.8 lbs. All data sheets per gm calls for 4lbs.

My problem is that my air takes forever to actually blow cool air. And when it does its not that cold. It's cool but not down right cold. It gets the job done but i guess i was expecting more since its all new. I have a new recirculation motor i need to install because the door isnt completely closing. Im going to put a temp gauge on the vents to check actual output temp vs ambient temp. So I will report back with that soon.

One thing that has me a little worried is the high and low lines that run to the rear are not at cold or hot as the lines in the bay. The rear lines are just Luke warm at best and barley cool to the touch. Not cold and wet like the front line or the dryer. I don't know if that is a symptom of anything.

I know this is a long post thanks for reading till the end. Any help will be greatly appreciated. Paul

Could the txv be causing these problems?

TXV could certainly be plugged. Sounds like you are undercharged too. Charge sticker for my '97 Burb calls for 4lbs, 4oz.

Edit: Also, you did take the orifice tube out of the new condenser when you installed it, correct? Most new condensers ship with a new tube installed in the outlet for the condenser, which is correct for most GMT400's, but not the dual system Suburbans. Having thought about it, it makes sense given your problem.

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I will check that. I guess I'll just go ahead and replace the txv if I'm gonna have to open the system up again anyway. Today is the hottest so far, and thus ac isn't cutting it. Even driving 55 mph it is pathetic.

99blueburb said:

I will check that. I guess I'll just go ahead and replace the txv if I'm gonna have to open the system up again anyway. Today is the hottest so far, and thus ac isn't cutting it. Even driving 55 mph it is pathetic.

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Pulling the TXV is a chore, to say the least. You have to pull the entire rear unit and split the case to access it. The quick connects for the heater lines are prone to falling apart from plastic embrittlement due to age and heat cycling. Evacuate the system, pull the grille off, disconnect the lower line from the condenser and check to see if the orifice is there. Should be quick and painless, and I betting that the tube is there. Having two tubes in the system will do exactly what you describe. Pull your vacuum and recharge and see what it does.


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I was also a little confused about the actual charge. My 98 tahoe with rear air calls for 4lbs 4oz. The sticker on my original dryer said 3lbs 8oz. The replacement dryer came with different stickers to replace with the correct charge as the one you removed. It had 2 for suburban one was 4.4 and the other was 3.8. Why would there be different charges for the same vehicle. Also the new condenser was considerably thinner than the one I removed.

I will definitely check the condenser Tuesday when I get back to work. That would be awesome if that's all it was. I spent $600 on my ac stuff just to be sure I was going to have my system in tip top shape, only to be disappointed.

Only thing I can think of for the charge discrepancy is for truck with rear air and trucks without rear air, as they use the same dryer.



This is what I based my charge from, as it was the same as the original unit.

Your new condenser may be a parallel flow unit instead of a serpentine flow unit that came on these trucks originally. They tend to be thinner due to smaller internal passages and thinner metal for better heat transfer.

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My original dryer said 3lbs 8oz and mine has the rear air so I don't know. When I recharge I'll put the 4lbs 4oz in it. I'll still do a before and after vent temp too and report back my findings after I check out the condenser. Thanks a lot u have been very helpful and knowledgeable.

If you have the HVAC machine, did you check the pressures to make sure they are at the correct readings, or low?