Refrigerant Charge - Montana van with and without Rear Heating / Cooling?

[1999montana]

Our van originally had front and rear air until a leak developed in the pipes leading to the the rear evaporator about 8 years after purchase. Actually, the leak appeared just under the firewall immediately above the steering shaft.

I converted the AC to front only by purchasing the correct pipes for front only AC after discovering it was cheaper to do that than have the dealer replace all the lines to the rear, a process the dealer said could not be guaranteed not to leak once completed!

Now, I need to re-charge the system because it was over-filled after the repairs were done; - it works, but not well. How much R-134 is required (by weight) to fill a vehicle without rear air?

[Tech II]

Not sure if I remember this right, but doesn't the capacity label on the vehicle in the engine compartment give both capacities?

What year?

For a 2002 Montana, 1.7 # for front only, 2.2 # with rear.....

[1999montana]

Originally Posted by Tech II

Not sure if I remember this right, but doesn't the capacity label on the vehicle in the engine compartment give both capacities?

What year?

For a 2002 Montana, 1.7 # for front only, 2.2 # with rear.....

Umm, '99 Montana?

Thanks again for the reply.

I'll check the label, I think it has the specs for the catalyst and emissions too... will have a look. 25 to 27 oz sounds about right for front only. I think AutoZone said 32 oz for front / rear, but I wasn't sure for front only.

Happy Memorial Day!

[rkvons]

Don't you just put gauges on it, start the vehicle and start adding Freon until the high and low side pressures are correct for the ambient air temperature?

[1999montana]

Originally Posted by rkvons

Don't you just put gauges on it, start the vehicle and start adding Freon until the high and low side pressures are correct for the ambient air temperature?

Yep, that would be the 'right' way to do it. I've ordered the gauge set from AutoZone and will see what happens once I get the right tools.

[brcidd]

Charge by weight is the "right " way to do it-- any other way is a WAG

[1999montana]

Originally Posted by brcidd

Charge by weight is the "right " way to do it-- any other way is a WAG

I kind of thought that too. Particularly since the 'kits' you can find for R-12A up here only have the low side gauge. I figured that if I had the right amount of refrigerant that charging an evacuated system should be a snap. Turned out that being able to see both sides helps to show if the system is over-charged, too much oil versus refrigerant perhaps, or if there is still a restriction (cleaned, but not newly replaced expansion valve) for instance. Doing it by weight in this case, didn't work for me.

Everyone I talked to insisted that having the gauges completed the story. Now, in addition to charging the evacuated system again (by weight), I can see the whole picture. Boy, I hate doing stuff twice, or even three times!