Tech | Refrigerant Charge
Today you'd be hard pressed to find a new vehicle on a dealer's lot without factory air conditioning. Even 20 years ago in the early '90s the Mustang's A/C system was an option, though the majority of Mustangs sold had the Preferred Equipment Package (PEP) checked off on the order form. This included A/C, power windows and locks, and more. Dealer installed A/C kits were something many dealers, mostly in the northern states and Canada, still stocked for the customer who finally caved in and wanted A/C in their car. Going back even further to the '50s and '60s and you'd note just a few percent of new vehicles came with factory ordered A/C and dealer-installed kits were big ticket items that few could afford.
Of course as we get older and the '60s get farther away, we find it hard to believe so few went without the comfort of "conditioned air." This is why today many companies offer aftermarket performance A/C systems for classic Mustangs and Fords. Just flip through the catalogs from companies like Vintage Air, Hotrod Air, Classic Auto Air, and Old Air Products and you'll see everything from basic under dash kits to electronically controlled heat/air/defrost kits with fuel efficient Sanden rotary compressors. Of course, once you have the A/C installed it does require some seasonal maintenance for it to perform at its best, just like your home A/C system.
Often, due to the limited seasonal driving time of our classic Fords, our A/C systems develop small leaks that prevent the system from optimal cooling. If you've installed an R-134a-based system you can easily "top off" your system with a multitude of over-the-counter kits. Owners still using R-12-based systems, however, aren't as lucky since R-12 has been legislated out of use and requires a license to purchase. We found a non-ozone depleting climate safe product called Green Freeze that can be used in both R-12 and R-134a systems on top of the original refrigerant (to top off) or as a complete replacement. So now when your classic Ford needs that "one-can charge" to make your ride comfortable again for the summer you have a DIY option that will work and will even make your A/C system run more efficiently. Check it out.
All we did was back our '66...
All we did was back our '66 Mustang out of the garage and turn the A/C on and at idle we were greeted with an 82-degree vent temperature-darn near ambient with no real cooling effect. For summer driving comfort, this just wouldn't do.
Of course, getting the most...
Of course, getting the most from your classic Ford's A/C system isn't just about refrigerant levels. You need to ensure your system is fully operational with proper compressor-clutch air gap, solid electrical connections, an unobstructed evaporator drain, drive belts in good condition and properly tensioned, good airflow across the condenser, and so forth. A system with any mechanical issues isn't going to run well, no matter the refrigerant charge.
Due to the low mileage of...
Due to the low mileage of our Mustang (since the completion of the car's build), we knew our hardware was in order and that we had a small refrigerant leak. The stock Tecumseh compressors are getting harder to find in good shape and when not used regularly, the seals can pass refrigerant and oil. The brass service cap(s) will need to be removed for access to the system.
If recharging with R-12 from...
If recharging with R-12 from some hidden stash (we know many still have a supply in their workbench) you can thread the charging hose on directly, but in our case we're going to be using the recharging kit from Green Freeze, which requires an R-134a style adapter (included in the kit).
Green Freeze can supply you...
Green Freeze can supply you with just the refrigerant, or it can provide fittings, charging hoses, and more. Here, we've tapped our first can with the optional Green Freeze charging hose kit.
Since the classic Ford manifold...
Since the classic Ford manifold fittings do not use Schrader valves, you must connect your charging hose to the system before opening the manifold. A special manifold wrench is available for the small square drive fitting, but an adjustable wrench gets the job done too in a pinch.
Two cans later, our A/C gauge...
Two cans later, our A/C gauge was giving us a reading of 39 degrees. That's a 43-degree temperature drop and plenty cool to keep us comfortable on our next road rally or cruise.
Once charged, the manifold...
Once charged, the manifold must be closed before removing the charging kit/hoses. You have the option of leaving the adapter fitting in place and installing the plastic sealing cap (convenient if you must charge the system regularly) or you can remove the fitting and put your brass cap back in place for those who like the stock appearance.
One last follow up item to...
One last follow up item to consider, now that your classic Ford is making ice cubes once again, is ensuring that the cool air stays inside where it will do the most good. Check all door seals, adjust any ill-fitting glass, and so forth to keep the conditioned air inside. We found some cool air escaping into the engine compartment via the A/C hose grommet and simply sealed it with some 3M strip-caulk/putty.