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#725589 - July 11th 2017 9:01 pm A/c air help needed.  
Joined: Dec 2016
Posts: 41
Offgrid2 Offline
newbie
Offgrid2  Offline
newbie

Joined: Dec 2016
Posts: 41
East Tennessee
I have a 1994 g20 conversion van with front and rear ac. Since I bought it van the ac and air have not worked as they should.

The rear unit does not blow any air at all.

The front blow air on all fan speeds. Regardless of what air direction I set the controls to it will blow warm air to the windshield and footwell.

It has not blown cold air.

I tried a can of r134a, it would not go in, the gauge read in the red as overpressure.

Today I relieved some of the freon in the high valve. Now it will blow coldish air but everything is the same. I just replaced the blower motor resistor as the old one was rusty. No change. Tomorrow I am going to replace the blower relay.

Any ideas?

What about the blend door? Where is it located? Also is there a rear blower motor and if so where is it?

#725596 - July 11th 2017 11:44 pm Re: A/c air help needed. [Re: Offgrid2]  
Joined: Jul 2016
Posts: 71
BlairW Offline
journeyman
BlairW  Offline
journeyman

Joined: Jul 2016
Posts: 71
Saskatchewan
Well the blowing only on windshield will be a vacuum line not connected


1979 Nomad
2005 E350 Cutaway Class C
#725616 - July 12th 2017 9:00 am Re: A/c air help needed. [Re: Offgrid2]  
Joined: Nov 2013
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Wedgy Offline
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Wedgy  Offline
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Joined: Nov 2013
Posts: 669
West Texas
OG2,

My G30 rear air unit is located at the rear ceiling at the back doors. Yours may be inside the conversion cabinetry, but the vents should be visible. There are separate controls for the rear heat and air on the dash.

Yup, you have a controls issue in the dash, probably a simple problem, but a bear to get too. Not too worry.

Motor vehicles are a mechanical device, and they will break.
You will have a much better understanding of the repair process with a Factory Service Manual. Try Ebay, and be glad that it's a Chevy

Good Wrenching!


"Who New? Blue"
1990 Chevy G30 454
Church Van, maternity division

"Old Blue"
1988 Dodge B250

"Cabin Cruiser"
'94 Dodge B350 www.xplorermotorhome.com/
Xplorer MH model 230 230 hp MPI 360 LA Wedgy OD auto

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#725623 - July 12th 2017 11:55 am Re: A/c air help needed. [Re: Offgrid2]  
Joined: Dec 2016
Posts: 41
Offgrid2 Offline
newbie
Offgrid2  Offline
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Joined: Dec 2016
Posts: 41
East Tennessee
I have the service manual but it's a thousand miles away at the moment.

I am going to try and fix the front first before the rear.

I'll try and swap out the rear air dash switch first. On the passenger side behind the rear wheel wheel is the heating element, I guess there is a small motor behind it.

As for the front, today the cold air stopped blowing.

I looked at the black ball and followed the vacuum lines, the y splitter was indeed missing a vacuum line . I found the line and it is in bad shape from the heat. I am going to remove the doghouse and see where it goes and replace it. However reconnecting that vacuum line did not make a difference.

#725632 - July 12th 2017 3:35 pm Re: A/c air help needed. [Re: Offgrid2]  
Joined: Jul 2017
Posts: 1
houselift Offline
stranger
houselift  Offline
stranger

Joined: Jul 2017
Posts: 1
Nashville Tn
I have 2 chevy g20s. an 84 and a 90. both have a fuse box installed in the inside back for the aftermarket adds the conversion company installed. my 84 is factory rear air and the 90 is aftermarket.
I don't know if yours is factory or not but check for fuses for the fan motor. also both of mine has a circuit breaker for that fuse block mounted close to the battery.
Watch the compressor clutch to see if it is turning. It will not engage if the high side pressure is to high or to low.
My 90 had a vacuum leak on the air/heat control in the dash. I could hear it hissing inside the dash. Had to fix that.
Blairw is right. with no vacuum the air will default to air on windshield
A good cheap way to find vacuum leaks is to take a small hose and put one end on your ear and move the other end around the connectors etc. listen for hissing. a vacuum gauge is a good tool to have. if the needle is fluttering then you have a leak somewhere.
also sometimes the vacuum balls on the hood can get a crack in them.
The rear air never works as good as the front.
John

#725634 - July 12th 2017 6:20 pm Re: A/c air help needed. [Re: Offgrid2]  
Joined: Jun 2010
Posts: 12,178
frscke1 Offline
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Joined: Jun 2010
Posts: 12,178
Van Diego California
Welcome to the site John ....


SUNSHINE VANS-VAN DIEGO
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ONE FOR THE DIRT & ONE FOR THE STREETS
'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
'92 CHEVY G30 454 BEAUVILLE EXT 146" WB
#725669 - July 13th 2017 2:00 pm Re: A/c air help needed. [Re: Offgrid2]  
Joined: Dec 2016
Posts: 41
Offgrid2 Offline
newbie
Offgrid2  Offline
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Joined: Dec 2016
Posts: 41
East Tennessee
Thanks for the info. It is an aftermarket rear ac with a small fuse box behind the driver's seat. Last time I checked they looked good.

While I have been removing the trim around the gauge cluster and doghouse. The back of the fan switch looks burnt.

As for the front. I have replaced all the decaying vacuum lines but nothing has changed, everything looks plugged in behind the back of the HVAC controls.

#725670 - July 13th 2017 2:57 pm Re: A/c air help needed. [Re: Offgrid2]  
Joined: Aug 2001
Posts: 11,218
Reed Online content
Maniac
Reed  Online Content
Maniac

Joined: Aug 2001
Posts: 11,218
Fircrest, WA
Originally Posted by Offgrid2
I have a 1994 g20 conversion van with front and rear ac. Since I bought it van the ac and air have not worked as they should.
The rear unit does not blow any air at all.


Check the ground for the rear fan. Often the aftermarket rear AC units don't drain properly and moisture will collect under the housing and corrode the ground for the fan. I had this happen on my 89 E150 with aftermarket rear air.

Originally Posted by Offgrid2
The front blow air on all fan speeds. Regardless of what air direction I set the controls to it will blow warm air to the windshield and footwell.


I am not familiar with Chevies, but on Dodges the dash vent doors that direct air to the various outlets are controlled by a vacuum modules and work via hoses and bellows that open and shut the flaps in the dash. I know older GM cars I have worked on also had the vacuum controlled HVAC system. I would start by looking at your control head for the AC. Is the vacuum line to the intake manifold hooked up? Is the control head unit working? Are all the hoses under the dash connected? Are the bellows that operate the vent doors working?

Originally Posted by Offgrid2
It has not blown cold air.
I tried a can of r134a, it would not go in, the gauge read in the red as overpressure.
Today I relieved some of the freon in the high valve. Now it will blow coldish air but everything is the same.


That is not how you go about charging your AC system. Overfiulling the system will cause it to go int bypass mode and not run the compressor. You need to get a set of manifold gauges for the AC system and look at both high and low side pressures. Also, the ambient temperature and humidity play important roles in system pressure. You should never put in more refrigerant than the system is designed for.

The high system pressure and poor cooling may also be due to a clogged filter in the receiver/dryer.

All things considered, unless you are willing to get the right tools, get a factory service manual, and learn how to repair the system correctly, you will be better off taking the van to a qualified AC service tech.

Originally Posted by Offgrid2
I just replaced the blower motor resistor as the old one was rusty. No change.


No change to.......what? The blower motor resistor in the dash only effects the front blower motor. if your fornt blower motor works fine, then a rusty ballast resistor will not impede blower performance.

Originally Posted by Offgrid2
Tomorrow I am going to replace the blower relay.
Any ideas?


Again, why? If your front fan works, leave it alone. The rear fan operates independently of the front fan, does not have a resistor, and almost certainly does not have a relay.

Originally Posted by Offgrid2
What about the blend door?


See above. There are at least two- a hot/cold blend door and an output direction door that changes where the air comes out.

Originally Posted by Offgrid2
Where is it located?


Blend doors are in the dash vent assembly, down by the heater core.

Originally Posted by Offgrid2
Also is there a rear blower motor and if so where is it?


Yes, it is in the rear AC unit housing.


Windows- they're what make a van worth owning!
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#725674 - July 13th 2017 6:00 pm Re: A/c air help needed. [Re: Offgrid2]  
Joined: Dec 2016
Posts: 41
Offgrid2 Offline
newbie
Offgrid2  Offline
newbie

Joined: Dec 2016
Posts: 41
East Tennessee
After putting the doghouse back on. The front air is now operating on all HVAC controls. There is a vacuum leak I can hear when changing between air direction but it stops after a second. I do not know which line is leaking as they all made a solid connection when I was inspecting it.

Also the AC compressor will only turn on if I turn the clutch slightly when the engine is off. When I crank it, it fires right up.

#725692 - July 14th 2017 8:51 am Re: A/c air help needed. [Re: Offgrid2]  
Joined: Sep 2013
Posts: 510
tuner4life Offline
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tuner4life  Offline
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Joined: Sep 2013
Posts: 510
Indiana
I wonder if your A/C clutch is worn out. It's a magnetic clutch and many cars that I've worked on have shims that can be removed once the clutch is worn out and the gap between the clutch surfaces is too large for the magnet to be able to close. Removing the shims closes that gap back down and the clutch can work properly. I have no clue if your van is set up this way as I usually work on Imports, but every one I've ever seen uses the shims and can be fixed in that way.

Last edited by tuner4life; July 14th 2017 8:51 am.

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