2015 tahoe a/c

[travisk]

I have a 2015 tahoe that has had the compressor and condenser replaced recently. Compressor is aftermarket condenser is oem. Its definitely cooling a lot better than it was however, I was hoping for better (wifeys 2021 terrain blows 40 degree air after 20 mins idling). At idle my tahoe blows 58/60 degree air out after initial cabin headload has been removed (takes awhile) and with recirculate on. And about 48/50 degree air out the vents going down the highway. Vent temps are basically the same whether its 107 outside or 80 best it can do is 48/50 degree vent temp.

I'm In the dallas area. temps have been in the low 100's lately. I leave work about 8 every night and the drive home is where I notice its performance or lack there of the most.

 

[OR VietVet]

Inspect for blockage in front of condenser and at the cabin air filter. What are the gauge readings at what ambient temp? Why did you not change the orifice and the accumulator? When system was buttoned up, how long was it on vacuum? While opened up, did you flush system?

 

[swathdiver]

Could also be a temperature or recirc actuator letting heat into the system. The proper scan tool can show you commanded and actual temperatures. This is helpful since the computer controls the temperatures.

Sometimes the air coming out of mine is in the 60s, other times in the 30s as the computer decides what it needs to maintain the interior temperature.

Which aftermarket compressor did you use?

 

[travisk]

Inspect for blockage in front of condenser and at the cabin air filter. What are the gauge readings at what ambient temp? Why did you not change the orifice and the accumulator? When system was buttoned up, how long was it on vacuum? While opened up, did you flush system?

All work was done at the dealership. A lot of unknowns to your questions .Seemed like they were guessing. Replaced the compressor first. Did better but not as expected. Then Replaced condenser, said it was ready. There was nothing on the invoice saying anything about the oriface tube or accumulator being replaced. Going to assume it wasn't. Again work done at dealership don't know if there's a standard time for it to be on vacuum when work like this is being preformed or if a flush is standard practice either. Cabin air filter recently replaced.

 

[travisk]

Could also be a temperature or recirc actuator letting heat into the system. The proper scan tool can show you commanded and actual temperatures. This is helpful since the computer controls the temperatures.

Sometimes the air coming out of mine is in the 60s, other times in the 30s as the computer decides what it needs to maintain the interior temperature.

Which aftermarket compressor did you use?

I just put mine on low which I guess I just assumed it means it's blowing straight cold air and not trying to blend it in any way... Thought about crimping the heater hoses to see if that drops the temperature at all. Just seems odd that it blows basically 50° air no matter the outside temperature. It was shipped to the dealership by whoever carshield decided to go with. Don't really see any labels with the name on it on the compressor least not where I can get to it and see.

 

[OR VietVet]

The devil is in the details. A/C needs help to work correctly. I am asking about basics and I have never trusted dealerships to show an expertise in a lot of mechanical tasks they tackle. They are all about flagging hours. I also agree with @swathdiver, in that it could be A.I. related. IMO, I would find a trusted shop with a guy/girl that specialize in a/c work. Either that or take back to dealer and tell them you did not get what you paid for.

 

[travisk]

Thinking some of my issue might be partly in my head and maybe I shouldn't be expecting much better. Believe some of it is the ai also.
Part of the problem might also have been i was using a analog dial thermometer. Its actually doing a little better than i thought. setting bi-level and decreasing fan speed helps get the vent temp as low as 43.5degrees after bulk of heat load is removed from cabin.
Borrowed my buddies 3k snap on ethos scanner, and digital thermometer for the vent. And able now able to see more exact details of what's going on.

Following pics were taken on the way home at highway speeds.
Think you might also be onto something about it being the ai. On the way home it seems to peg the evap core temp at 39 (i know it can do better). As you can see from the following pics it can range as low as 33. That low peak was in park with me holding the rpms at 1800 and ive seen it down to 32 shortly after take off from idle after dropping cabin temp from 105 to 95. Only way to get the evap core temp down from 55-60degrees at idle (at least initially from cold start) is to hold the rpms up around 1800 for a minute or so, it will drop evap core temp down to 41-44degress when the cabin temp is 105.

Using the scanner has allowed me to see what settings allow the evaporator to get the coolest and there by allowing vent temps to get their coolest. Bi level and 60% or lower fan speed seems to give me 43.5 vent temps (by my vent gauge anyways, i know the pics show a lil different) after bulk of heat load has been removed. which is actually pretty cool when ya think about it i guess and is acceptable.

I guess my next questions are and where my problems are
Why wont it get evap temp very low at idle upon initial start without helping it by increasing rpms manually? (like i said after you hold rpms higher for literally 1 minute, evap temp drops significantly then its able to hold itself there at idle)
Why does it seem to peg evap temp at 39 going down the highway when it can do 33 in park? should be able to to better or at least as good with more airflow over condenser. im guessing ai is holding it back for some reason.
Why are my radiator/condenser fans allowed to shut off if i dont have the ac blower fan at 100%? This sucks, my evaporator core and vent temps rise 20-25 degrees within seconds without the radiator fan pulling air across the condenser. It goes from a nice cool 44-45 degrees at idle to blowing 65-70degree air out the vents. Also just noticed this on the way to work sitting at a red light. Guess the truck thinks the coolant temp is good and disregards the the ac is still on and shuts off the fans.

 

[TahoeFL2017]

All technical stuff aside - I'm in Tampa Bay, and it's about as hot and humid as it gets pretty much anywhere in the country in July.

I've had my Tahoe in the shop twice now, after being disappointed with AC blowing not-so-cold, and me trying to keep the revs up, and thinking that at idle or stopped at lights, the AC maybe needed more revs, etc

AC HAS to work right in Florida summers - period.

Both times was serviced at my trusted dealer, I avoided cheaper independents - one butchered my Toyota so bad I traded it in - AC service can be an art form in my experience, so I'd rather pay more and get it right.

Both times, the shop fixed the AC, and it freezes me out, and I regretted not taking it in sooner.

Your AC should be cold at idle, easily, if not something is wrong.

(think of all the cops who sit and idle daily with the AC blasting)

 

[Bigkevschopshop]

So there is a sensor that blends or reduces ac to keep evap from freezing up. It was faulty in my ride, the evap would freeze up at low fan speed, but it would get cold for sure. But evidently yours is working correctly, It will try to maintain above freezing temps to keep it from icing up. Your vent temp on low fan should be in low 40s. I think the evap temp in the high 30s is spot on and is working right. That's why it kind of adjusts on you without your input.

So if you watch the pressures, when you rev it up the pressures will drop on the low side and get you in the good cold zone of operation with lower pressures on the low side and an increase on the high side pressure. You may be over or under charged or there is some air in the system. Air or improper charge are the two normal factors with ac issues.

Another possible issue is air flow, the high side switch to request fan speed from the cooling fan on the condenser is set pretty high if I remember right. You will find that just even going 45 mph at almost idle rpm its cooling better than sitting, this is part to do with the programming of what high pressure is needed to trip fan into max mode.

On a cold start in 100 degrees, 50 or 60 out of the vent is all you could ask for when the interior is 135 roughly, its alot of thermal load. In 10 minutes down the road it should really start getting cool then . My black burb takes 15 to 20 before I reduce the fan speed from 3/4 to 1/2. Just to give you an idea for food for thought.

Your ambient temp that day with the scanner was 86 and your high side was 130. that seems low to me.

 

[travisk]

Thanks for the reply BigKev, i was hoping id get one from someone with basically the same make and model. only thing i have access to compare it directly with is my wifes 2021 gmc terrain. And it will freeze ur d*k off within 20 mins of it idling in the driveway in the direct midday sun. its the newer 1234yr refidgerntat and several years newer so im guessing thats part of the difference. Mine seems to take forever to cool down and when it gets there it doesn't want to stay.

The differences i notice with it are the evap does get a lil cooler but for the most part it does seem to keep the evap at around 35-39 also on max fan speed at idle, cooler the longer it sits.. It does creep lower, ive seen it down to 28, but never does it creep higher then 41 when fluctuating. Tahoe evap temp will hold around 41 at max fan speed at idel but also creeps as high as 46. the terrains evap vs vent temps are alot closer also. when it gets good and cool its blowing a constant 39 degree temp out the vent at max with evap mostly stable holding at 35. tahoe blows out 47-49 at max fan speed with evap sitting at 39. to get it down to 43 the blower speed MUST be turned down and even then the evap fluctuates to much to keep it blowing a steady 43 itll eventually creep higher.

Sounds like its very similar to what yours is capable of doing but i think mine is fluctuating a little more. And im wondering if it doesn't have to do with the same issue as to why the condenser/radiator fans are shutting off completely at a certain point. Thinking the Ai is adjusting the rad/condenser fans up and down ever slow slightly causing the evap to fluctuate up and down and then for whatever reason shutting them of completely. which then ofcourse sends temps rocketing.

Dropped it of at a difference dealership saturday. got a ahold of em to today. Them basically saying that's the best it can do blah blah blah. cant find anything wrong to repair....
I'm like obviously the fans shutting off when the ac is running sending vent temps rocketing is not the best it can do and they needed to spend a little longer looking into that issue... Said they were gonna park it outside and let it idle try to duplicate the fan problem...