The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1988 - 1998 GMT400 Chevy & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 09-15-2018, 07:04 PM   #1
jwinga
Registered User
 
Join Date: May 2013
Location: wilcox county ga
Posts: 23
99 two door Tahoe AC help

This is my sons Tahoe and the AC is about to get the better of both of us.
What’s been done so far-
New compressor
New hoses
New receiver/dryer
New condenser
New expansion valve (black)
Flushed out evaporator
Vacuumed the system down for two hours.
Compressor came with 3 ounces of oil added 4 ounces, two in compressor and two in recieiver dryer, gave the compressor a few spins by hand after putting on the hoses
Added two full 12 ounce cans and maybe half of another.
Low side pressure about 55-56
High side 230 ish
Vent temp around 68
Outside temperature at the time was around 90
Both heater hoses clamped shut with vice grips
It will get the receiver/dryer and the hose going back to the compressor sweaty and the evaporator is dripping a little.
AND it still doesn’t cool, any ideas?
Attached Images
   

Last edited by jwinga; 09-16-2018 at 07:55 AM.
jwinga is offline   Reply With Quote
Old 09-16-2018, 12:43 AM   #2
Sim6
Registered User
 
Sim6's Avatar
 
Join Date: Feb 2015
Location: Centerton, AR
Posts: 407
Re: 99 two door Tahoe AC help

Temp control panel is operating correctly? Make sure the temp control knob wasn't cracked, just spinning on the shaft? Have you tested your pressure control switches? Pressures look good, Is your compressor cycling normal? I'm not an expert in AC just a few things I had to trouble shoot recently.
Jeff
__________________
53' Chevy 3100 5 window http://67-72chevytrucks.com/vboard/s...d.php?t=660793
Sim6 is offline   Reply With Quote
Old 09-16-2018, 07:58 AM   #3
jwinga
Registered User
 
Join Date: May 2013
Location: wilcox county ga
Posts: 23
Re: 99 two door Tahoe AC help

Compressor comes on and stays on. The control panel appears to be ok, everything lights up, vent positions and defrost work correctly and blows hot air or cool when the temperature control is turned.
jwinga is offline   Reply With Quote
Old 09-16-2018, 08:37 AM   #4
speedygonzales
Registered User
 
speedygonzales's Avatar
 
Join Date: Jan 2006
Location: Smithfield, VA
Posts: 1,345
Need a little more information

Even though your pressures look ok, when you vacuumed it down, did you leave it sit with the vac pump off for a good while to be sure it held vacuum? Sorry we don't know these things if it isn't written. One would expect if it was leaking, the numbers would be off.

I stopped relying on the rudimentary gauge on the vacuum pumps years ago and only vacuum with a "micron" gauge. https://www.trutechtools.com/MicronGauges
Several times I have gotten to the end of the vacuum pump gauge only to discover later there was still a leak. If you can achieve 500 microns of vacuum (using the micron gauge obviously) or lower, you instantly know there is no leak. But that's beside the point of your problem.

OK you mentioned outside is 90 and vent temp is 68. Do we assume the air temp going into the AC is 90? If that's the case, you have a delta of 22.

Over 20 is acceptable. Much more than that is hard to achieve. Now if you tell us the doors were closed and it was in recirculate and the air going in the intake was 80, you would have a problem.

From the photo it appears you have 64. There are 5 divisions in a 20 span on the gauge therefore each division is 4. Also, those gauges are notoriously wrong by varying amounts. It's always a good idea before using it, to put in a glass of ice water to be sure of 32F/0C.

Did you close the windows and put it on recirculate and see what the temp was after about 20 minutes? You have to remember we don't know how you tried it, how long you tried it and what was the temp inside the vehicle (even though the outside was 90).

I was not aware of an expansion valve in these vehicles. Only an orifice tube. Is that what you meant by "black"?
__________________
99 Z71 (98 body style)
Pride and joy

Last edited by speedygonzales; 09-16-2018 at 09:18 AM.
speedygonzales is offline   Reply With Quote
Old 09-16-2018, 10:28 AM   #5
jwinga
Registered User
 
Join Date: May 2013
Location: wilcox county ga
Posts: 23
Re: 99 two door Tahoe AC help

Orifice tube, the different colors (white or black) are to determine use with or without rear AC. The black is supposedly are for units without rear AC.
Temperatures is with doors shut and recirculate on.
Used regular AC gauges for vacuum because thats what Ive got. Pulled a vacuum until the needle was against the stop. Waited an hour or so, the needle was still against the stop, then ran vacuum pump for an hour before charging.
jwinga is offline   Reply With Quote
Old 09-18-2018, 04:55 PM   #6
EVRLET
Junior Member
 
EVRLET's Avatar
 
Join Date: Aug 2015
Location: Las Vegas NV
Posts: 71
Re: 99 two door Tahoe AC help

I have a 99 Tahoe 2dr and the capacity is 36 oz of R134. If you put 2.5 cans, that’s only 30 oz.

http://www.techchoiceparts.com/refri...et-light-truck
__________________
Customization is what you want it to look like -- not what other people think it should look like
EVRLET is offline   Reply With Quote
Old 09-19-2018, 05:55 AM   #7
jwinga
Registered User
 
Join Date: May 2013
Location: wilcox county ga
Posts: 23
Re: 99 two door Tahoe AC help

I was using this chart for pressures, the low pressure is on the upper end for the temperature range. When I began adding the last can it began to cool less instead of better.
Ive got a different orifice tube, Im going to evacuate the system replace it, vacuum it down, recharge and try again.
Attached Images
 
jwinga is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 05:28 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com