Poor AC performance - Heat turns on automatically

[nimrod.sixty9]

So after a full flush of all lines, replacement of clogged orifice tube, vacuum and recharge I still have poor AC performance. 40/150psi @90* Front vents (and floor because it wouldnt stop blowing there) were less then 90, but rear was hot.
After research I came across re-calibration procedures. Seems everything was working as described. Until after the process was complete. After a few seconds the AC straight up goes hot, even if I go flat out to 60*. Thoughts?
2004 Tahoe

 

[swathdiver]

So after a full flush of all lines, replacement of clogged orifice tube, vacuum and recharge I still have poor AC performance. 40/150psi @90* Front vents (and floor because it wouldnt stop blowing there) were less then 90, but rear was hot.
After research I came across re-calibration procedures. Seems everything was working as described. Until after the process was complete. After a few seconds the AC straight up goes hot, even if I go flat out to 60*. Thoughts?
2004 Tahoe

Are there any BCM codes? If you have a bi-directional scan tool, you should be able to see the commanded and actual state of the actuators and then command them into position if they are out of position, assuming the motors still work.

 

[nimrod.sixty9]

Are there any BCM codes? If you have a bi-directional scan tool, you should be able to see the commanded and actual state of the actuators and then command them into position if they are out of position, assuming the motors still work.

That I dont have.
It seems to have stabilized, and unfortunately Ive discovered a new issue, it seems previous owners have done some hack job to the evap enclosure. I feel a lot of heat coming out of their not so great patch job. Now off to find a tear down of the enclosure.
Still issue with rear AC tho. Maybe expansion valve?

 

[nimrod.sixty9]

Pulled off all the garbage. They had some other plastic that was terrible at sealing. Also feel like there is too much gap around the evap. ie air flow bypassing the evap. Would some of that expanding foam sealant work good in this instance?

 

[89Suburban]

Pulled off all the garbage. They had some other plastic that was terrible at sealing. Also feel like there is too much gap around the evap. ie air flow bypassing the evap. Would some of that expanding foam sealant work good in this instance?

I would worry about molding issues if going to use foam. Maybe pickup some vinyl or plastic sheeting, or some kind of plastic laying around the garage like old oil jugs or trash can lid or something. Trim to fit and build a new cover using silicone adhesive?

 

[nimrod.sixty9]

I would worry about molding issues if going to use foam. Maybe pickup some vinyl or plastic sheeting, or some kind of plastic laying around the garage like old oil jugs or trash can lid or something. Trim to fit and build a new cover using silicone adhesive?

The foam Im referring to is for home insulation so I would think (hope) it is very mold resistant.
As for plastic, that is what was on there. With it there was at least 1 1/2 gap for air to flow around the evap. IDK if that would be by design as I dont have another enclosure to compare to. I already taped it back up, seems a little cooler, but air flow is still quite terrible. Evap and blower look off the shelf new.

Ive also noticed the blower is quite slow to start up. Dont know if that is common or sign of another issue.

 

[Eod1]

I hate to say this because I know we are all looking to save money. Saving money means spending it somewhere else I get it. Unfortunately out here in AZ it's already 111 degrees right now and I have to have air conditioning that works and my time is money. Like I said I hate to say this but take it the chevy and say fix this. It might cost 1k or 2k but when their done it will be back to factory and blowing cold as ****. Anything else I would say do it your self and save as much as possible but a working airconditioner is a must have. My dog will not ride with me if he isn't cold. He is my number 1 the wife is number 2

 

[Eod1]

O also if you get Dynamat and put it in the ceiling, floor doors and side. Basically cover everything it will help keep the cool air in and hot air out. It's a little salty but it a one time buy. Best thing you can do for the money.

 

[nimrod.sixty9]

I hate to say this because I know we are all looking to save money. Saving money means spending it somewhere else I get it. Unfortunately out here in AZ it's already 111 degrees right now and I have to have air conditioning that works and my time is money. Like I said I hate to say this but take it the chevy and say fix this. It might cost 1k or 2k but when their done it will be back to factory and blowing cold as ****. Anything else I would say do it your self and save as much as possible but a working airconditioner is a must have. My dog will not ride with me if he isn't cold. He is my number 1 the wife is number 2

No thanks. The whole truck was 1500 and I can work on my vehicles all day. I have fixed numerous AC systems but there are particular things in every vehicle, hence why I asked here. No AC tech would have likely known about the blend door reset procedure. Trying to figure out if there is something else that I might not know about in these trucks. My guess is the compressor is weak and the blend door actuator is going bad.

 

[swathdiver]

So after a full flush of all lines, replacement of clogged orifice tube, vacuum and recharge I still have poor AC performance. 40/150psi @90* Front vents (and floor because it wouldnt stop blowing there) were less then 90, but rear was hot.
After research I came across re-calibration procedures. Seems everything was working as described. Until after the process was complete. After a few seconds the AC straight up goes hot, even if I go flat out to 60*. Thoughts?
2004 Tahoe

How often do you get over to Fort Pierce and Port Saint Lucie? If you can get to me, I don't mind putting my Tech-2 on it to have a look around.

 

[nimrod.sixty9]

How often do you get over to Fort Pierce and Port Saint Lucie? If you can get to me, I don't mind putting my Tech-2 on it to have a look around.

That would be so awesome of you!
Im over fairly often actually.
Whats your schedule like?

 

[swathdiver]

That would be so awesome of you!
Im over fairly often actually.
Whats your schedule like?

Not sure yet. We're supposed to be at our church on Midway Road around 1030-1100 for about 60-90 minutes but that depends on when my daughter comes back up from West Palm. Not sure yet if I'm working tonight or tomorrow evening either, sorry. Saturday should prove to be more stable, I'll be at home until about 6 pm.

 

[nimrod.sixty9]

So I now have the enclosure wrapped up in Gaffe tape (much better).
I decided to pull back a portion to feel the temp of the Evap after touching the lines near the drier. Hi side is hot and low side is super cold. So thought to do the same with the evap.

So reached in and felt the evap on outlet side (red) had a ton of condensation and was much colder than what Im feeling at the vents. But also while on that side, I felt a ton of heat... hot rather. Fan had lots of flow on both sides (blue), but almost feels like I get more from opposite of blower motor; both were cool or cold.

Im curious to the the internal operation of the enclosure. Does anyone have a schematic?

Not sure yet. We're supposed to be at our church on Midway Road around 1030-1100 for about 60-90 minutes but that depends on when my daughter comes back up from West Palm. Not sure yet if I'm working tonight or tomorrow evening either, sorry. Saturday should prove to be more stable, I'll be at home until about 6 pm.

Hey bud I replied to your PM
Thanks!

 

[swathdiver]

So I now have the enclosure wrapped up in Gaffe tape (much better).
I decided to pull back a portion to feel the temp of the Evap after touching the lines near the drier. Hi side is hot and low side is super cold. So thought to do the same with the evap.

So reached in and felt the evap on outlet side (red) had a ton of condensation and was much colder than what Im feeling at the vents. But also while on that side, I felt a ton of heat... hot rather. Fan had lots of flow on both sides (blue), but almost feels like I get more from opposite of blower motor; both were cool or cold.

Im curious to the the internal operation of the enclosure. Does anyone have a schematic?

View attachment 226898



Hey bud I replied to your PM
Thanks!

Did someone cut away the plastic and expose the evaporator?

 

[BG1988]

make sure the condenser is clean as well Bugs can get caked on and it does not take very many to hamper a/c performance....

there is some caked on my dads (not very much)

and it does not even work

all you get is slightly cooler muggy air even after having it serviced

after i cleaned my condenser it has better performance
since I noticed when if got warmer there was less performance

it gets cool with in 10 seconds of turn it on... good as new



also make sure both fans are coming on

 

[nimrod.sixty9]

make sure the condenser is clean as well Bugs can get caked on and it does not take very many to hamper a/c performance....

there is some caked on my dads (not very much)

and it does not even work

all you get is slightly cooler muggy air even after having it serviced

after i cleaned my condenser it has better performance
since I noticed when if got warmer there was less performance

it gets cool with in 10 seconds of turn it on... good as new



also make sure both fans are coming on

Thanks!
The condenser is clean tho.
The evap is ice cold.
Please see update above, Id love your input on the new observations
Fan is good to go too.

 

[nimrod.sixty9]

Did someone cut away the plastic and expose the evaporator?

Yes sir. Evap looks new along with blower.
I have peeked inside and both doors are closed on heater core so that is fine.
My money is now on the actuator that controls the where the airflow goes.
I made adjustments on the controller and didnt see it move. It also blows out of floor and vents at all times; never changes. Im wondering if there is a perfect point in the adjustment that causes terrible air flow... also being exactly there the actuator failed.

 

[BG1988]

Yes sir. Evap looks new along with blower.
I have peeked inside and both doors are closed on heater core so that is fine.
My money is now on the actuator that controls the where the airflow goes.
I made adjustments on the controller and didnt see it move. It also blows out of floor and vents at all times; never changes. Im wondering if there is a perfect point in the adjustment that causes terrible air flow... also being exactly there the actuator failed.

does it blow cold in the rear? the rear has an another blower

 

[nimrod.sixty9]

does it blow cold in the rear? the rear has an another blower

I havent checked in a bit, but last time i did, it was hot

 

[BG1988]

the rear A/C is independent of the front A/C(blower and actuators ) controller wise. . do check it (the only thing the front controls is the masterbutton power switch)


if it gets cold then the A/C is working and there is an issue with the actuators/wires or controller to the front... This would be the first thing i would do when trouble shooting.


does the outside temperature gage work? (on the mirror this is part of the A/C circuit )'


instead of throwing money at it


my dad wasted money servicing his A/C spent 200$
still was blowing warm muggy smelly soggy air

I fixed it in 5 min with some soap and a tooth bush.