Automotive Air Conditioning Information Forum (Archives)

derrybermw on Sun July 17, 2011 3:10 PM

Year: 67
Make: Ford
Model: Mustang
Engine Size: 289
Refrigerant Type: R12
Ambient Temp: 97
Pressure Low: 7
Pressure High: 135
Country of Origin: United States

I have a 67 mustang with an R12 A/C system. This is a factory A/C (in dash) system. The original compressor (possibly other parts as well) was replaced with a Sanden unit by a previous owner. Last year, I checked the pressure and found it was in normal ranges, but cooling performance has never been able to keep up with the heat here in Texas. To my uneducated eye, the system was working properly, condensation was coming out of the drip hose, low side connections were very cold (frosting in some cases), high side connections were hot, but register temps were only slightly cool to the touch. I seem to recall they were in the 40-50 degree range, but can't remember for sure. Bottom line is that anytime the temperature was above about 85 degrees, this system could not keep up.

This season, I noticed it was not cooling at all and began checking things out. I noticed a black oily residue on the main hose connection coming out of the high side of the compressor. There is the same oily residue on the expansion valve, but I think that was there last year as well. So, it looks like I have a leak on a system that was already not cooling properly.

My question is this. Should I invest in a complete new system from Classic Auto Air or Vintage Air, or should I try to fix the one I have now?

--mike

bromodragonfly on Sun July 17, 2011 3:49 PM

If you have the means, I would recover what's left in the system, pressure test, fix any leaks, change drier, evacuate and recharge with spec weight of r12.

Just because the low side of the system is sweating heavily or frosting, does not mean that you will get that temperature of cooling out of the vents. Many times, frosted lines and not-so-frosty vent temps is a result of an undercharge.

Pressures you listed are quite low. My guess is you've been slowly leaking over the past couple years, and cooling has decreased proportionally with the leak.

Personally, I would keep the stock system.



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There is no knowledge that is not power

caveeagle on Sun July 17, 2011 4:31 PM

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mark

caveeagle on Sun July 17, 2011 4:47 PM

I am new to working on ac systems, but I know quite a bit about 67 mustangs. I have owned 3 of them over the years. 'Still have my '67 vert, although I don't drive it much.

One of my '67 coupes, did have the original factory (in dash) ac system. This was the first year that mustangs were offered with the in-dash system. The 65-66 cars could only be had with the under-dash add-on style units. FWIW.

The new classic auto air system would probably work better than the factory original unit, but i think those kits are designed around an upgrade to a non-ac car. You can probably make it work, but there may be some alterations to a standard install. I have seen people who have added these systems using the stock center and side vents. This looks much better than the aftermarket vents that come with the kit. You should ask CAA if your Stock AC controls will work with this kit. IIRC, it is set up to work with the stock non-ac heater controls.

My factory system worked ok, but never really offered impressive cooling. The decision to keep your stock system or upgrade would hinge on a couple factors for me:
>how much do you drive your stang?
>How much does the originality factor mean to you? For 95% of 67 stangs, I would not give this a second thought. If the car has collector value, lie a GT, GTA or Shelby, I would leave it stock.
>Are you capable of restoring the stock unit? By now it probably needs a complete overhaul to have any chance if it working properly. Vacuum lines and new seals for the evap core box will help a lot.
>Consider a 50% conversion to a modern compressor, R134a and a refurbished Evap/control box may be good enough.

I would like to add ac to my '67 vert so I can get more use out of it in the hot FL weather. I am really impressed by the engineering of the new CAA units. If I follow through with it, I plan to install their kit and buy some original ac vents, to I can retain the stock look.

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mark

Dougflas on Sun July 17, 2011 6:36 PM

The add on kits with R12 had sight glasses on the driers that were great for charging purposes. 1200 rpm and clear the sight glass. Then add 2 oz more R12

derrybermw on Sun July 17, 2011 11:30 PM

A few more details about the car that I failed to mention earlier: The low side connections only feel slightly cool and there is no frosting on the fittings or condensation coming from the drip tube. On a 100 degree day, the register temp is about 90-95 degrees.

Concerning Mark's questions about driving habits and originality, I would drive the car every day if it were not so dang hot and I am not terribly concerned with originality. Other than being a fastback, the car is not all that unique. You mention the engineering of the Custom Auto Air systems. I am curious to hear everyone's thoughts as to how the aftermarket systems compare to the design and performance of the factory systems. I have heard some complaints about the inability of the aftermarket systems to utilize fresh (outside) air and to be able to blend air. More than that though, I want to know if either system offers a significant cooling advantage.

My preference is to fix the current system rather than install an aftermarket system. This is not so much any concerns over originality, I just have heard that R12 will perform better than R134. Also, it seems like the shorter route to resolution vs a complete replacement of all components. Bottom line is I want to get this resolved once and for all so that I can use the car more. Any additional advice would be greatly appreciated.

JJM on Mon July 18, 2011 12:29 PM

Considering the R-12 factory spec on this vehicle is only 28 oz, keep the system all original and R-12. Pressure reading indicate a low charge.

It makes no sense to put an aftermarket A/C system on a vehicle already equipped with A/C.

Given the age of the vehicle, the receiver/dryer, hoses, seals, TXV (because of possible leak) should be replaced and the system flushed thoroughly. Not a big $$$ cost for A/C. If it were my Mustang, I'd pull the Sanden out and install the correct compressor for the vehicle. You should also clean the exterior of the condenser and especially the evaporator - after 44 years, it's bound to be pretty dirty.

Joe

TRB on Mon July 18, 2011 12:31 PM

OT- Joe did you get my email?

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