Rear AC Block Off Question

[Johnny Racer]

I am going to be blocking off my rear AC this week and was trying to find out on here (thought I seen it somewhere but cant find it now), how many pounds of freon do I charge the system with once the rear AC is blocked off?

Truck is a 1999 4 door Yukon.

Thanks in advance.

 

[Tbruz]

Front only AC system is 36 oz; Front with Aux Ac(rear ) is 64 oz.

You should evaluate where/how you are blocking the rear off.

The front only systems( which I have on my 97 2 door) have an Orifice Tube in the liquid return line(lower line) of the condensor.
I believe the front/rear systems DO not have an OT in the lower line but rather have an THX(thermal expamsion valve) located at the rear evaporator.


Tbruz

 

[Immortalmort]

Any writeups/threads available for how to do this? Have a full shop available, but A/C repairs aren't very common around here

 

[_Dylan_]

Front only AC system is 36 oz; Front with Aux Ac(rear ) is 64 oz.

You should evaluate where/how you are blocking the rear off.

The front only systems( which I have on my 97 2 door) have an Orifice Tube in the liquid return line(lower line) of the condensor.
I believe the front/rear systems DO not have an OT in the lower line but rather have an THX(thermal expamsion valve) located at the rear evaporator.


Tbruz

I think the orifice for trucks with rear a/c is on the lines going to the rear a/c. I'm not sure how you are going to disable it.

Why do you want to? Lines rusting out?

 

[Johnny Racer]

One of my lines ruptured end of last season and dont want to spend a million dollars replacing them. So I got the block off kit and capped them off right at the firewall. Recharged the system, clean the blower motor/evap core and housing now blows ice cubes at me on the second fan speed setting and it was 106 heat index here in Chicago today.

 

[Immortalmort]

same here, one of the rear lines blew out while charging it & the others don't look too far behind. Was thinking of capping it off right at the condenser, but not sure of any special fitment for capping off the rear lines? there are threaded lines coming out of the condenser that I should be able to cap off no problem, just not sure if any standard bolt would work or if i need something special for the pressure/aluminum.

 

[SunlitComet]

The rear system uses a thermal expansion valve. The front uses a fixed orifice tube. They best way to charge a system after you block out a rear section is evacuate it at least 28-29 inhg for at least an hour. While the system still under a vacuum with the vacuum pump isolated from the system introduce refrigerant and after the vacuum goes away the pressure will start to build. You will need a minimum of the front only refrigerant load and add as needed to get the proper performance from it.

 

[Popeye]

So I got the block off kit and capped them off right at the firewall.

Could i have the part # for the Block off Kit. i have the same issue and have tried all kinds of shut off options, none have worked.
thanks in advance.

 

[SunlitComet]

I hate seeing A/C units being disabled.

 

[Johnny Racer]

I hated disabling it but it was cheaper than replacing the lines. Thats next summers project.

Here is the link to the auction where I bought mine: http://www.ebay.com/itm/Rear-A-C-block-off-kit-90-1999-Suburban-Chevy-GMC-Aux-AC-Elimination-NEW-/181201437761?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a30728441