'72 454 A/C repair - continued

[Randall K.]

Last night was not the first time I've stood looking into the engine bay thinking "I should have bought a car with the base engine"...

I need to get the A/C core box out to remove the A/C hose assembly (hopelessly stuck), check the evaporator core for leaks (too much twisting trying to remove the hose assembly?), replace seals and to repair a hole in the box itself. I've not found a way to be able to rotate the box and get it out. It is completely loose from the firewall.

Is there a trick? I did check the Service manual, and not knowing all the terms completely, I may have missed something. Should I separate the fan half from the A/C core half of the housing? I think this is 6 large screws that I can see from various angles.

Thanks
Randy

[Bill C.]

Re: '72 454 A/C repair - continued

I am not 100% sure here, but I have a feeling that the only way the unit is coming out of the engine compartment is with the engine out

There is not nearly any room, and to be honest - I had a HELL of a time getting mine in with the body off the frame.

[Randall K.]

Re: '72 454 A/C repair - continued

I'm seeing a number of postings on the Corvette Forum that indicate that the evaporator core box is relatively easy to remove if the two halves are separated. If this works, then my next challenge will be installing new seals and getting everything back together without disturbing the seals.

I'm going to try this removal over the weekend - will post results on Monday.

Thanks
Randy

[Jim T.]

Re: '72 454 A/C repair - continued

Randall do you know for a fact that your concealed evaporator core is leaking inside the housing?

I don't know if the electronic sniffer that my home air conditioner serviceman used the other day when my 7 year old Trane was low on R22 will work with detecting an R12 leak, but this is something you could check on with someone in the air conditioning field.

If a check can be made and a confirmation that your evaporator is not leaking, it would sure save you a lot of work in removing it and finding no leak.
How is your evaporator going to be checked it if you do remove it?

My factory air 1970 (daily driver in 1988) stopped cooling. I was out of state on business and told my wife to take the car to our only Chevrolet dealer. (They sponsored our Corvette club).
They told her it needed a new evaporator. She told them to fix it.
They could not unbolt the largest fitting at the top evaporator fitting. They even drilled a hold in the nut thinking this would help. The still could not get the big fitting undone.
They gave up and said they could not do the job. I am so very glad they gave up and also so glad they did not drill through the nut into the evaporator line fitting.
I returned and read my service manual and the symptons that fit my 1970's air conditioner problem was right there in print with even a picture of what I needed to remove.
The line coming from the condensor connects to the expansion valve and this is where the problem was.

At this connection there is a metal filter, cone shaped, that traps debris. My 70's metal filter was compacted with dessicant from the dryer. The dessicant is bagged in the dryer and it busted/broke and allowed the dessicant to travel to the expansion valve.
The metal filter did its job.
Cleaned the filter, replaced the dryer, cleaned the travel path from the dryer to the expansion valve.
Had the air conditioner system professionally serviced with a vacuum pull, new oil, and R12.
My 70's air is still operational today although I think it is time to replace the front seal in the original compressor.

The serviceman for my Trane was the owner of the company that also sold me my unit and told me the leak is so small as detected by his sniffer that I could just get my unit recharged every wo years or every year if it needs it. The condensor is guaranteed for 10 years, but as old as my unit is he is going to check about the evaporator still being under warranty.
A small leak in the evaporator might be something a person can live with even as expensive as R12 today with an top off. Having the sight glass in the dryer it is very easy to verify when the system needs more R12.

[Randall K.]

Re: '72 454 A/C repair - continued

Jim - thanks for the response. I'll make sure I check the filter as well.

My original problem is that one of the hoses from the compressor hose assembly has ruptured, and I cannot budge the other end at the POA valve. The fitting from the POA valve to the evaporator core is equally stuck - otherwise, I could have avoided the core box removal.

Unfortunately, this means I'm reduced to removing the evaporator core box and getting it onto a bench for better leverage. I've tried every tool I can get my hands on - and modified a few as well (including crowfoot flare wrenches).

The other issue that I discovered early on after surveying the situation is that there is a hole in the evaporator core box (probably about 2 square inches of area) - looks like it ran into a corner of the exhaust manifold at some point.

I replaced the ceramic seal in my compressor 2 years ago (A/C shop showed me the leak using dye), and it worked great until the hose ruptured.

I'm open to other suggestions...

Thanks
Randy

[Jim T.]

Re: '72 454 A/C repair - continued

Without looking at my 70 I cannot visualize your ruptured hose. Will look later.
Can the ruptured hose portion be removed and leave enough to splice in a metal tubing and secured with clamps. Older Corvettes like my once owned 64 had clamps to secure the air conditioning hoses to compressor.

[Randall K.]

Re: '72 454 A/C repair - core box out!

Update... it is possible to remove the AC evaporator core box from a big block car if you remove the 7 screws that hold the two halves together. The 7th screw is a small sheet metal screw accessible from underneath. The evaporator half slides up and out fairly easily. The fan half has to be rotated toward the centerline of the car, making sure that it doesn't get caught on any hoses or wires, and then it will JUST squeeze out.

I also found at least 80 cubic inches of dirt, leaves and pine needles inside the core box, which couldn't have helped air flow! I also can now see that the other hose in the compressor hose assembly appears ready for a rupture, as it's showing similar signs of damage/decomposition that I already saw on the hose that did rupture.

Has anyone ever installed a screen at the outside air intake to prevent this from happening?

Thanks to all who commented.

Randy

[Larry M.]

Re: '72 454 A/C repair - continued

Randall do you know for a fact that your concealed evaporator core is leaking inside the housing?

I don't know if the electronic sniffer that my home air conditioner serviceman used the other day when my 7 year old Trane was low on R22 will work with detecting an R12 leak, but this is something you could check on with someone in the air conditioning field.

Jim and Randy:

Yes, the leak detector for a R22 system can also be used for R12. Should even work on R134a, but perhaps not as effectively.

I purchased one for my car (and home) a year or so ago. Works well, especially for evaporator and compressor seal troubleshooting.....where a dye or leak solution check is difficult or impossible. Recommend the Inficon TEK-MATE testor. I did a lot of research before buying this one. It is the cheapest one that will reliability work for R12 and R22 systems, and has been used in the AC industry for years. Costs about $200, if I remember correctly.

If you have a friend who is an AC repairman/technician, that is the way to go. Or take a road trip to New Orleans and use mine. I know my neighbors like to use it.

Larry

[Gary J.]

Re: '72 454 A/C repair - continued

Dr. Rebuild should have your hoses and seal kit in stock when you start back. I can only image the twisting and turning you did to get the two halfs out.

[Randall K.]

Re: '72 454 A/C repair - continued

Given the horror stories posted on this forum, it really wasn't all that bad once I found the 7th screw and separated the halves. The fan half was a little tight, but not impossible - the evaporator half pretty much lifted straight up and out. I did have to get a LOT of stuff out of the way before this was possible.

I'll try to take some pictures as I'm reinstalling during the next month or so, and post them to this forum.

I've visited the doctor once, and will need to go again, now that I can see what I need!