A/C Question

[S Enriquez]

I recently bought a 1990 SHO - a/c does not work, how can I tell if it's been converted, the previous owner didn't know. Also, what is entailed in converting it, i heard you need a new orifice, new rings and of course r134a. Any help would be appreciated.

 

[jelloslug]

If it has threaded valves that look like the valve stems on your tires on your service ports, is has not been converted. If it has connections that look like big air line fittings it has been converted. You must also romove as much of the old oil as possable and you have to replace the drier. You will also need to find out why it leaked down to begin with. Could be a bad o-ring, could be a bad compressor, who knows?

 

[rangerj]

SE,

If the A/C gauge connection ports have black caps it is R-12. R-134a caps will be red on the high pressure side, and light blue on the suction side.

The following is a brief descriptiion of the conversion process.

Replace the filter/dryer (Ford refers to it as an accumulator/dryer)

Replace the oriface line

Pull the condenser and have it pressure tested for leaks, them clean it out with a chemical cleaner (Kit available from most auto parts stores).

Use the kit to clean out the evaporator core. You blow the chemicals through the firewall connections after the oriface line and the suction lines are removed.

The chemical cleaner removes any R-12 oil residue, and any other crap in the cores.

Drain the compressor of any R-12 oil. DO NOT CLEAN THE COMPRESSOR,. JUST DRAIN IT. Remove the clutch assembly from the compressor and check the compressor shaft seal for any signs of a leak. If none, reassemble and continue.

Get a conversion kit that has new R-134a compatible "O" rings, new garter springs, and R-134a oil made for conversions. These kits are available at most auto parts stores.

Put 5 ounces of the oil in the compressor, then attach the manifold lines. The attached lines will keep the oil from spilling out when the compressor is mounted. Spin the compressor by hand about 20 times to distribute the oil in the compressor.

Apply a thin coat of oil to the "O" rings at the connections. Put one ounce of oil in the condenser, one ounce in the accumulator/dryer line and the remaining ounce (minus the amount you used on the "O" rings) in the oriface line.

Make all connections.

Vacuum to 27 to 30 inches of vacuum for 45 minutes to an hour. Then let sit for an hour and check for leak down (leaks). If any leaks, fix them, then vacuum again. Once you have no leaks, vacuum for another 30 minutes to an hour.

Moisture will boil at room temperature under the vacuum. This why it is important to vacuum. Moisture (water) can destroy a compressor.

Lastly, charge with about 27 to 30 ounces of R-134a. Low side pressure should be about 50psi and high side pressure should be about 250psi. The temperature comming out the vent should be below 40 degrees (34 to 36 is the usual for a system in good shape).

It is not as easy as it sounds but it is do-able! rangerj

 

[S Enriquez]

This is all good stuff, appreciate the help - perhaps one more thing, part numbers, ugh - are places like autozone helpful, or do any of you guys know the part number for the a/c lines high side and low (they look like crap) - and the dryer-also, silly question, can i rent a vacuum or do I have to go to a shop and do this? Any help is greatly appreciated. Thanks.

 

[jelloslug]

Nice write up rangerj. thumbup I am about to convert my system over soon also. Its not the first one I have done, but I have never seen a good procedure written out for doing a change over eather. This one's getting printed.

 

[rangerj]

S E,

You can get the oriface and acumulator/dryer as aftermarket parts from auto zone, NAPA, Federated, Car Quest, Pep Boys, O'Riley's, etc.

If you want to stay all OEM parts go to fordpartsonline, or do a google search for Ford parts. The two lines are not SHO specific. The compressor is SHO specific.

Auto Zone will let you use a vacuum and guages. You have to leave a hefty deposit, but it beats having to buy a vacuum and gauges you would only use occasionally.

drdave is in the process of doing a conversion and should be done soon. Maybe we can talk him into giving us a report on how things went. What was easy, what was hard, what to avoid, what I would do different, etc.

Maybe if you both ask him real nice he'll do that. What about it doc? rangerj

 

[S Enriquez]

what do you say, i'll buy you a beer

 

[ATXSHO93]

Good a/c post.

I just converted my '93 ATX to 134a and it works well. The only thing that I would add is that to use Nylog on all of the O-rings. It is a honey like O-ring sealant that works very well. You can get it from ackits.com

Replacing the accumulator in a SHO is a PITA. I had to take apart my fuel line connections at the fuel rail, passenger side wiring bundles, ECT. to thread it through. Well worth the effort since R-12 is up to $86.00 a pound around here.

Good luck