Ermond

What is the correct pressure on the high side and the low side of the Ac? 1993 YJ.

Roler

Depends on ambient temperature

Saudade

R-12 or R-134a? I think '93 was still R-12 but you or an earlier owner may have changed over.

dzywicki

The pressure will vary depending on the ambient temperature. If you are doing AC work, make sure you get a set of gauges. This site has a chart.

Ermond

it is R12, and I have the manifold gauges and the ambient temperature is going to be 86°. I just don’t know on this old Jeep what the high-pressure and low pressure readings should be when fully charged

Saudade

Is it already empty? If so, after evacuating, it takes 38 oz of R-12 for a full charge.

The '93 FSM says:
A/C SYSTEMS SPECIFICATIONS
SPECIFICATIONS TABLE

Application Specification
Compressor Type ................ Sanden SD-709 7-Cyl.

Compressor Belt Tension
Serpentine Belt
New ...................... 180-200 lbs. (82-91 kg)
Used ..................... 140-160 lbs. (64-73 kg)

System Oil Capacity ........................ 4.6 ozs.

Refrigerant (R-12) Capacity
Cherokee ................................ 38.0 ozs.
Wrangler ................................ 32.0 ozs.

System Operating Pressures
High Side .......... 160-235 psi (11.2-16.5 kg/cm  )
Low Side ............... 30-35 psi (2.1-2.5 kg/cm  )

Saudade

Unless you already have the R-12, I suggest you convert to R-134a while you still can as even R-134a is being phased out.

My '88 is still R-12 and I have 3 cans left that I bought quite a while ago..Even though I'm Sect 608 certified and can purchase R-12, it's gotten to expensive to maintain. Once my supply of R-12 is gone, I'm converting.

Ermond

Thank you Saudade, there is still some pressure in the system. I have never converted a 12 to 134a before, what is involved in doing so?