Charging A/C on a Gen 1 SHO

[DeepPower]

The system should be charged such the pressure maintains approximately the 45-50 psig during operation.

The target pressure is dependent upon the refrigerant and the ambient temperature. The pressure gauge should have a temperature scale on it also. The higher the ambient temperature, the higher the pressure.

I just had my '89 SHO converted to R134a. Eh, not as cold as Freon. There was some hassles, new system would not hold a charge. My mechanic put in some "A/C Pro Super Seal" which stopped the leaks, but he recommended that I might need to recharge once every few weeks.

I've been looking at the recharge kits with the built-in gauges, but I've been warned that the target pressure depends upon the ambient temperature, per the above post, and it's best to get the pressure/temperature specs for the particular vehicle.

Can anyone please post the pressure/temperature scale for charging my A/C? Thanks!

 

[zak]

Most gauge sets are color coded i.e. you don;t want high side to be in the yellow or red - unlikely to get there anyway using chargette cans.

I usually do it by compressor on time, off time and total cycle time vs the lookup graphs in the factory service manual (which vary with temp). You can get this from any Ford factory (Helms) manual for a car that uses 134a.

Hope that they didn't do a death kit on you . . .

 

[DeepPower]

Yes, but the color varies by car. What might be green for most cars can be in the red zone for a Ford SUV. That's why I asked about finding the temperature/pressure chart for the '89 SHO.

 

[Airborne]

But, on a system that is old and has a potential to leak, R12 will stay in the system. R134 will leak where R12 would not. People blame leaks on R134 when converting systems from R12. But, in reality, R134 will not leak out of a well maintained system.

To do it right the system needs to be flushed of the contaminants (stop leak) and the leaks sealed up correctly. New O-rings are cheap and don't damage your system. That stop leak stuff wreaks havoc on AC systems, especially fixed orifice tube systems and will reduce the efficiency of an already weak system.

 

[probe_racer]

hmmm if you paid to have the conversion done then tell them to fix the leaks properly. leaking that much refrigerant to need to feel every few weeks its not acceptable. the system will get moisture in there and will create more issues such as clogging of orifice tube and dead of your compressor.

proper way to do it is to have at least all seals changed, orifice tube, ac receiver drier and full flush of system as well as adding the correct amount of oil to the ac system. and then pull vacuum on it and see that it holds vacuum before adding R134. if it is done at home at least add a tiny bit of dye leak detector (it will make not affect the cooling effect of your system, unless u add a ton) to make it easier to track and find leaks when they happen.

good luck though.

keep us posted.

 

[DeepPower]

Thank you for all your comments, and especially to Airborne for the manual pages.. Let me explain...

This was very very much an issue of time and money. Tomorrow (Sunday) I leave Boston for good and drive to Long Island NY where I stay with family, at just before dawn Tuesday morning, when the SHO and I set out to drive to Dallas, Texas where a great job is waiting for me.

Mechanic started work on Tuesday with my laundry list of maintenance issues - replace some suspension bushings, bleed rear brakes, replace front brake pads, balance tires & alignment, and more. And with movers and all, as you can imagine this is a horribly expensive month for me as my new company isn't paying for the move up-front, they are reimbursing.

As complications with the A/C developed it was a case of how fast could we get any replacement components. There was also a good chance that many of the A/C fittings would break when taken apart as it's been years since they were touched. We discussed the best course of action and I decided that the plan was first the Stop-Leak. If that didn't work, we'd have no choice but to see if we could have parts frantically shipped in time. Thankfully, the stop-leak has worked and the A/C seems to be holding a charge. But my mechanic has warned me that we can't tell after only a few days if there are any leaks or not, so I'm the one that wants to bring a recharge can with me on the drive down to Texas.

The secret to using the stop-leak is to let the A/C run for an hour so the stuff has a chance to evenly distribute itself.

Once in Texas my next step is to change hoses, o-rings, etc. but first I must find a COMPETENT mechanic in the Arlington/Mansfield area - any suggestions?

For the 1,700 mile drive my dashboard will have my Android tablet running Waze. For those that are interested, I started a Taurus SHO Waze group.