84 GMC 1500, Air Conditioning questions.

[Isotope]

I acquired an 84 GMC 1500, which was a project that is literally 96% complete. The truck runs great, has a late model Late Model Vortec / Cenerbolt Head 350, Rowdy Comp Cam, Street Warrior Intake, Edelbrock Carb, Aluminum Headers w/ Lock Bolts, 700R4 Overdrive Automatic Trans, 2500 Stall, a newer interior, with a new Air Conditioning system.


The problem I am suffering from is somewhat confusing issue to me as I am by no means an A/C guy. When I engage the Air Conditioning, the truck loses significant power, to the point of stalling, or nearly stalling, regardless of if I am traveling at a high rate of speed, or if I am idling, any suggestions?


I also noticed that the vent on the driver side, nearest to the door is not blowing anything from the vent; regardless of if I have the unit set to Vent, or attempting to use the Air Conditioning, or heat. May I ask for guidance regarding tracking down any diagram which will allow me to take apart the lower portion of the dash to investigate if I am missing a vent connection?


I spent a significant amount of time looking through the forum; however, I am unsure as to if, or when the units change between years. For that reason, I thought it would be best to ask.

Thanks in advance,
Iso

 

[Snoots]

First, check ALL of the vacuum lines for the HVAC.

It sounds as though you have a vacuum leak.

 

[Red Rex]

For your vent issue check that the duct hose behind the glove box is connected. My 84 model has a habit of slipping off

 

[Isotope]

First, check ALL of the vacuum lines for the HVAC.

It sounds as though you have a vacuum leak.

Will do, thanks for your time... I will report back.

 

[Isotope]

For your vent issue check that the duct hose behind the glove box is connected. My 84 model has a habit of slipping off

I will look at that shortly. Does the glove box need to come all the way out, in order to check the duct hose?

 

[Craig 85]

No you don't have to pull the glove box. I have my A/C system out right now to rebuild it. Here's the hose set up. I did not include the defrost vents. You may be missing the tube with the white tag or it slipped off on the right side. Look behind the ash tray.

Also, losing lots of power is normal. I had a fully equipped Calif. emissions '79 K15 with a 350. 165HP was stock. It was a dog with the A/C on.

You must be registered for see images attach

You must be registered for see images attach

 

[Backfoot100]

For your vent issue check that the duct hose behind the glove box is connected. My 84 model has a habit of slipping off
I will look at that shortly. Does the glove box need to come all the way out, in order to check the duct hose?


Sorry guys. I'm still trying to figure out how to make multi posts here so in the mean time I just copy/paste.

Had the same issue with my 86. You can reach up underneath thw glove box and check it.

The factory AC setup has a solenoid attached to the stock QJ that has a rod that pops out when the AC is turned on. This rod engages with the throttle plate and is completely adjustable to add a little higher idle which eliminates your problem. Mine works perfectly for that exact reason.
Sounds like you need to find out what that equivalent part is associated with your AC system and either install it or fix it.

 

[Backfoot100]

Crap...I just reread this. I told you about the passenger side vent duct.
The driver side duct is exactly as Craig85 pointed out.
You can get to it easily from under the dash on the driver side but you have to first remove the plastic and metal covers that are just underneath the steering wheel at the bottom the dash. Thats the only way you can R&R that duct.

 

[Isotope]

Crap...I just reread this. I told you about the passenger side vent duct.
The driver side duct is exactly as Craig85 pointed out.
You can get to it easily from under the dash on the driver side but you have to first remove the plastic and metal covers that are just underneath the steering wheel at the bottom the dash. Thats the only way you can R&R that duct.

Perfect, I will have a look shortly and report back. Does the driver side vent plug into the system just as the passenger side?

 

[Isotope]

No you don't have to pull the glove box. I have my A/C system out right now to rebuild it. Here's the hose set up. I did not include the defrost vents. You may be missing the tube with the white tag or it slipped off on the right side. Look behind the ash tray.

Also, losing lots of power is normal. I had a fully equipped Calif. emissions '79 K15 with a 350. 165HP was stock. It was a dog with the A/C on.

You must be registered for see images attach

You must be registered for see images attach

Thank you. I will have a look shortly.

 

[Backfoot100]

Perfect, I will have a look shortly and report back. Does the driver side vent plug into the system just as the passenger side?

Yes, all the way over by the ash tray.

 

[Craig 85]

Yes, all the way over by the ash tray.

There is a flexible hose that connects from the main A/C housing to the right dash duct. It's the round fitting on the upper right in my second picture.

 

[Isotope]

There is a flexible hose that connects from the main A/C housing to the right dash duct. It's the round fitting on the upper right in my second picture.

Nailed it - THANK YOU!

 

[Charlie]