Random air conditioning blows hot air

jigfeett

Full Member
Joined
May 30, 2008
Messages
127
Likes
3
Points
18
#1
Please fill out the following to ask a question.

MAKE: Chevrolet
MODEL: Trailblazer
YEAR: 2002
MILES: 165000
ENGINE: 4.2
DESCRIBE ISSUE....A/C random blows hot air.

2002 chevrolet Trailblazer LTZ

Electronic dual climate controls

Random A/C issue, 98° ambient going along @ 70mph blowing cold air

And for no reason blows hot air, blower speed & duct location did not change

Stopped & checked the fuses and relays in engine comp & in passenger compartment

Actually swapped each out with known good fuses and relays

At this time compressor was not activating & accumulator was not iced over

Continued on road trip & about 100 miles along A/C just started blowing cold air again.

When I got home I checked the charge with my Robin air 34788NI and found it to be low.02 ounces, so I recovered and recharged to spec. I read Alldata and found there is a low pressure switch tsb issue

Bought the AC Delco switch that is called out in the tsb for randon A/C issue switch did not fix the issue as several days later the A/C randomly blew hot air

I understand there is a HVAC program update but I cannot check it and dealer said bring it in and for $130 they would check it service guy was a bit of a jerk so I will call dealer where car was bought

I would think with the vin # any dealer could look it up?

This car was bought from the original owner & she said if there were any updates and the dealer notified her, updates were done.

I think this is one of those electrical gremlins

Any thoughts or help is much appreciated.

Thank you

Rob
 
Joined
Nov 14, 2006
Messages
4,742
Likes
43
Points
48
Age
117
#2
I found this - IDK
 

Attachments

jigfeett

Full Member
Joined
May 30, 2008
Messages
127
Likes
3
Points
18
#3
Added info, the car did have a history code for
U1152 loss of heating vent/air conditioning communication.
 

jigfeett

Full Member
Joined
May 30, 2008
Messages
127
Likes
3
Points
18
#4
Thank you, yes I saw that and that was the irritating part when I called the dealer and all they wanted to do is charge $130 to tell if it is up to date. Do you know if a dealer can look it up or not?
thanks
 
Joined
Nov 14, 2006
Messages
4,742
Likes
43
Points
48
Age
117
#5
if it was done by an authorized GM dealer it should be in the vehicle service history.
Any GM dealer can search vin # history.


IF and SHOULD are no guarantee -

GTG
 

jigfeett

Full Member
Joined
May 30, 2008
Messages
127
Likes
3
Points
18
#7
Update so far 3 more dealers have said bring it in $130 to hook up. I think I am stuck with doing so just to be sure software is at correct level.
I will update when I get this part done.
Thanks
 

jigfeett

Full Member
Joined
May 30, 2008
Messages
127
Likes
3
Points
18
#8
I havene't done anything with this because it is now cold so will pick it back up later.
 

EricC

Hero Member
Joined
Nov 14, 2006
Messages
423
Likes
3
Points
18
Location
Tulsa, OK
Website
facebook.com
#10
So we're clear, you've called 4 dealerships to ask if this update has been performed on your GM vehicle and none of them would look it up and give you a straight answer? If that's the case, did you ask to speak to the service manager? The general manager?
 
Joined
Aug 28, 2007
Messages
4,676
Likes
17
Points
38
#11
Another fellow on the board with MVAC problems was due to a lack of a good power on reset. His alternator voltage was low. Age old problem ever since they started putting computers in vehicles. Your system is erratic, with sensor problems or even with code problems, it will never work again.

If those program counters are not reset to zero, reads random code and all kinds of strange things can happen.
 

jigfeett

Full Member
Joined
May 30, 2008
Messages
127
Likes
3
Points
18
#12
Hello, time to revisit this post as the weather is warming up. Yesterday the A/C did it again in the heat of the day but in the evening I rechecked and cold as would be expected.

Eric, yes I did call a total of 4 dealers with the same answer of " bring it in it's$1xx.xx hundreds to check it out" and not one could or would look anything up as far as a programming update.
I think I will call a higher level manager when time permits.

Nick, I will check the charging system.

thanks again I will post an update as information comes in.
 

jigfeett

Full Member
Joined
May 30, 2008
Messages
127
Likes
3
Points
18
#13
Update, sent car to the dealer and paid $145 + tax and shop supplies for full system A/C Diagnostic.
They said the accumulator and condenser were clogging up because desiccant was breaking free.
They said the high side was low and the low side was high, OK let's go with that, only because the service tech probably experiences these types of issues somewhat regularly. I noticed the same readings but didn't think much of it. my bad.
Now when you look at the flow in an A/C system one would see it flow to the evap then to the pump then to the condenser and then the accumulator, so I would think the entire system would be degraded and would require replacement of all parts? I don't know but I'll find out when
I replace what the dealer said to replace.
Dealer $1200+ tax for accumulator and condenser.
I bought AC Delco parts for $121 + tax
I will replace these parts asap and give an update.
Thanks
 
Joined
Nov 14, 2006
Messages
1,478
Likes
15
Points
38
Location
Nothern California
#14
The fact that you just overhauled an automatic trans makes me confident that you will be able to do this
A/C job well also. Good luck to you.