I am getting ready to overhaul the a/c in my 98 expy. The truck does not have rear a/c and it is a 5.4 with 110,000 miles on it.

The compressor started dripping oil and losing charge about 2 years ago. I just kept adding the r134 with stop leak and it would hold for about 6-8 months. Well now it has caught up to me. Even though the system has a full charge the air isnt cold anymore and the lines under the hood get so hot you cant touch them. Im guessing all that stop leak has clogged the orifice tube preventing flow. So I have purchased a new compressor, drier/receiver, orifice tube, o-rings as well as a manifold guage set and a vacuum pump to do the job.

The compressor is already filled with oil (its tagged) and I know that I have to flush out the remaining parts of the system.

My questions are 1. Where exactly is the orifice tube located and do I need a special tool to remove/install it? 2. How much vacuum should I pull before its ready to charge? 3. What type of oil should I use to lube the o-rings? And lastly, what should my readings be when its fully operational? ( I have a Matco manifold guage)

Im not a newbie when it comes to vehicles I just never had to work on a a/c system till now.

Thanks and enjoy the holiday!

 

The orifice is in the line between the condensor and evaporator and you should be able to pull it out with needle nose pliers. I usually pull 30" of vacuum for at least 15 minutes. That ensures all moisture gets boiled out of the system and you know there are no leaks. Ford says to use mineral oil on the o-rings but I always use the compressor oil. They say the PAG oil attracts moisture but I haven't had any problems. Pressure readings at idle should be around 200-250 high and 30-50 low on max A/C depending on outside air temp and humidity.

 

Thanks. That exactly what I was looking for.