1973 Corvette Coupe A/C Re-charge Question

[Thomas R.]

I am having trouble finding a fitting for the schrader valve on the low side (Dryer). My normal A/C Gauge Hoses have a 45 degree bend that connects with the dryer schrader valve for the low side NORMALLY but, it just misses connecting to the valve because the cooling coil box is to close so, the hose fitting is just blocked.

I tried using a schrader 45 degree coupling but it has even less clearance. It is an original dryer unit with the valve pointing directly at the cooling coil box about 5/8" clearance.

Would appreciate any thoughts/suggestions. Trying to keep it original. I do know, it could be charged off the high side.

[Mark E.]

Re: !973 Corvette Coupe A/C Re-charge Question

Thomas,

The high and low pressure connection valves are located on the aluminum line manifold that's bolted to the rear of the compressor. You should see the valves pointing up. There's another low pressure connection at the VIR (which is what you're probably referring to as the dryer). Sometimes replacement VIRs are clocked differently, which may explain why you're having difficulty.

If you haven't done this before, consider referring to the service manual. It's important to not over or under charge the system. YouTube has a bunch of how-to videos as well.

[Thomas R.]

Re: !973 Corvette Coupe A/C Re-charge Question

Mark,

Thanks. The original compressor hose manifold only has one valve for the high side; the low side valve is on the dryer unit under the passenger side fender pointing at the cooling coil in the heater box. The clearance is 5/8" maybe 3/4" so that gap does not allow the gauges 45 degree hose fitting to fit. Would you know of any gauge hoses that might have a 90 degree bend. I've check aour here in Albuquerque and looked on line with no luck. I even went to a local hose builder who did not have a 90 degree fitting that would work. The GM after repair says cut the low side compressor hose and put a "T" fitting in and use clamps to seal it I think I may end up going that route. Thanks for you note.

[Mark E.]

Re: !973 Corvette Coupe A/C Re-charge Question

I just looked up the 1973 manifold/hose assembly and it looks like it only has one port as you say (manifolds up to '72 have two).

It's been awhile since I had my '73 (my first Corvette!) so maybe someone can verify this: I don't recall the low pressure port on the VIR difficult to reach.
Can your VIR be clocked differently for better access to the port?

[Thomas R.]

Re: !973 Corvette Coupe A/C Re-charge Question

Mark,

I wish I could clock VIR but, the cooling coil in the heater box is one solid tub going out to the top of VIR.

I was hoping some one knew of a special schradar valve tool GM used during building. I appreciate your thoughts and suggestions. If any of your local buddies have a 73 may be they have dealt with this issue. I don't have anyone with a 73 A/C equipped here in Albuquerque.

Thanks again.

[Mark E.]

Re: !973 Corvette Coupe A/C Re-charge Question

Hopefully a '73-74 owner will chime in.

I found this eBay listing with a photo of the evap box and VIR. Does this look like yours? Hard to tell but the port looks accessable.

https://www.ebay.com/itm/392607068141

[Russ S.]

Re: !973 Corvette Coupe A/C Re-charge Question

73 manifolds do only have the one port and the low side is on the VIR. The low side is almost impossible to attach to as installed from the factory. Many years ago on my 73 that I purchased new in 73, I actually bent the port on the VIR in order to acquire clearance to attach the hose.

I just looked up the 1973 manifold/hose assembly and it looks like it only has one port as you say (manifolds up to '72 have two).

It's been awhile since I had my '73 (my first Corvette!) so maybe someone can verify this: I don't recall the low pressure port on the VIR difficult to reach.
Can your VIR be clocked differently for better access to the port?

[Mark E.]

Re: !973 Corvette Coupe A/C Re-charge Question

Page 1A-52 of the '73 Service Manual says "Install Gauge Adapters J-5420 and J-9459 onto the high and low pressure lines of the Charging Station".
Page 1A-182 has a photo of the J-9459 "90 degree Gauge Line Adapter". It looks like its description: a tight 90 degree adapter. Could this adapter be what you need? I'm wondering if a well equipped AC shop has this type of adapter for these situations.

BTW, page 1A-51 of the manual says "Both high and low pressure fittings are located on the compressor connector block. A low pressure fitting is also located on the VIR unit." Incorrect information? Or maybe a running change? But it makes you wonder: If the car had both fittings on the compressor connector block, why are special adapters needed?

[Thomas R.]

Re: !973 Corvette Coupe A/C Re-charge Question

Mark, Yes, it is exactly correct for the 73 (thanks for finding it) I would like to send you a photo of unit with my notes where the distance of the valve to the heater box. It's hard to see in the photo but, the schradar valve cap is about 5/8" from the fiber heater box. I can't attach photo to the thread. My E-mail is tomrostkow@aol.com if; you want me to send the photo, please let me know an E-mail address I can use to send photo too.

Thanks Much Tom

[Larry M.]

Re: !973 Corvette Coupe A/C Re-charge Question

Tom:

Will this work??

https://www.zoro.com/jb-industries-quick-coupler-14-in-mxf-90-deg-33113n/i/G0730554/

Larry

[Mark E.]

Re: !973 Corvette Coupe A/C Re-charge Question

Here's a photo from the eBay listing above that the OP, Thomas, marked up. Thomas comments "I circled the valve cap area; you have to look really close, but the wall of the heater box extends past the metal plate as you look head on.The VIR/Dryer unit is original correct; I bought the 73 new. I have changed the manifold hose section twice over the years and had the A6 compressor rebuilt once."

Thomas- It looks tight but an adapter like what Larry found may be worth a try. Shops have been getting this done somehow since '73.

73 AC.jpg

[Thomas R.]

Re: !973 Corvette Coupe A/C Re-charge Question

Mark,

Looks great. Thanks for posting. I'll checkout Larry's suggestion.
Stay well, Tom

[Larry M.]

Re: !973 Corvette Coupe A/C Re-charge Question

I have NOT worked on a 73 AC Corvette, but for many other Corvettes and cars, it it needed for gage manifold connections. I have a couple like it in my toolbox.

If I recall, I needed for 67 big block AC Corvette on the discharge side.

Larry

[Thomas R.]

Re: !973 Corvette Coupe A/C Re-charge Question

Larry,

Thanks, it appears to be the closet answer so, I'm going to order and see how the clearance works out.

Much appreciated.

Stay well,

tom

[Thomas R.]

Re: !973 Corvette Coupe A/C Re-charge Question

Larry,

I did get the part but, it too just did not make the clearance between the valve and the heater box wall. I'm going to investigate charging the system from the high side. It is aslice device for hooking up, it would have been great, thamks for the tip.

Tom