Hi,

I have an 85 F-150 that I am converting to R-134a. I bought a new (refurbished) compressor, a new accumulator/dryer, new red orifice tube, o-rings, new pressure sensor, PAG-46 oil and 134a conversion fittings.

After vacuuming the system for about 45 mins, I started to charge it. At first the compressor wouldn't come on but then I found out that the ground for the AC compressor had become disconnected (it grounds in the cab under the dash and alll of that is pulled out.

Once I got the compressor running, it made a clicking sound whenever it would cut on. I took a short video that you can watch here:

http://www.sbsmotorsports.com/ac_noise.mov

Does this sound normal? I ended up putting two cans of freon in. The total I should have in it is three. Inside, I couldn't feel the air blowing cold at all. Shouldn't the system blow a little cold with a 2/3 fill?

A few questions:

1) When you fill it up from empty, about how long should it take for the system to suck in a whole 12 oz can? For me it was 5-10 minutes each can.

2) If you got to watch the video... do you think I need a new compressor? I hate to waste the $20 I spent in oil and freon.

3) The compressor would only stay on for about 1 1/2 seconds at a time. The pressure went down from 44 to 20 whenever the compressor would kick on. I'm attributing this to a partial 134a charge. What do you think?

Any suggestions would be greatly appreciated!


Thanks,
Sal

 

You'll probably need to adjust your low pressure cycling switch.. usually located on the accumulator. If you unplug the connector you'll see a standard screw head in there between the terminals. You can adjust this screw to adjust at what pressures it kicks off the compressor... Play with this screw 1/4 turn at a time.

The reason your compressor is cycling is either because you're still low on freon, or it's too cool outside to deliver proper pressures. (you want 70-75% the amount of R134 than you would need with R12... I like to overcharge older vehicles on a conversion by .2 to .3 lbs to improve performance while moving - although typically not as cold sitting still due to less air flow across the condensor)

Also R134a typically runs a higher high pressure, and a lower low pressure. Being your cycling switch is calibrated for a R12 it probably kicks off the compressor at 30-35 PSI. You probably want to adjust it to kick off at 15-20PSI instead.

It typically takes only a minute or two to suck down a can of freon, but being your compressor is cycling I can understand why it took so long.

Two things you should have done - 1> Flushed the system out while it was apart and 2> Manually primed the compressor with oil before installing. The truck kicking on a dry compressor can tear them up instantly. Flushing isn't so important unless you had some kind of blockage or a complete compressor failure.

Good luck.

 

Hi,

To add to my original post... I did take all of the AC parts out of the truck and flushed them. I also put 6 oz. of oil in the compressor and turned it by hand ~20 times before putting it in the truck. The other 2 oz. of oil went in the evap.

Any suggestions on the noise?


Thanks,
Sal

 

The 1986 f150 holds 48 oz of R12
Converted 1986 f159 will hold 38oz of R134a

The low pressure Clutch cycling switch on the accumulator has a small flatheaded screw that you can adjust.
Turn the screw CCW (screw out) 1/4 turn at a time until the low cut off pressure is about 25-28psi

the screw is between the electrical terminals.

 

It sounds like you are still undercharged, but that's just a guess without knowing the high side pressure. If you didn't add oil directly to the compressor and the charge is still low, the compressor is starving for oil. This will cause the noise.
Charging takes longer with cooler ambient temps. Try submerging the can in a bucket of warm water.
What brand is your reman compressor? If it's a Four Seasons, it could very well be defective right out of the box. Their quality leaves much to be desired.

Oops, I missed the post where you added oil to the compressor.