I have a 1990 7.3 liter ford truck (diesel). I don't have a lot of knowledge when it comes to autos, however, I am tired of paying mechanics for parts I do not need. I purchase used U-hauls and use them for my business so I am constantly repairing something. Currently, I have a truck that the ac compressor went bad on and I have the new replacement ready to install. I have been told that if I replace the compressor I also need to replace the drier. Can anyone tell me if this is necessary and why?

 

It's better to replace the drier while the system is empty rather then later when you find out you should have. If the existing compressor did not contaminate the system with metal debris..you can get by without the new drier. You should however remove and inspect the orffice tube if the system uses one.

 

The drier acts as a filter for the AC system. I had rebuilt the AC in the wifes Jeep last year completely. The compressor went out again last week and I just replaced it. The high pressure side was a lot higher then it should be, a new drier would have prevented that. Im rolling the dice with not replacing it, the AC blows cold now, but for how long. Unless the rest of your components are fairly new I wouldnt recommend skipping the drier.

Im not a AC mechanic, nor do I play one on TV.


B

 

I am a A/C guy by trade. I agree with everything you have been told.
A couple more ideas. Was the oil black and gooey? Did the orfice tube have gunk or chunks of metal on it? Was the orifice tube stuck in place?
If any of the above are true you have experienced "black death" It happens when the compressor is on its last leg and overheats the oil in the a/c system.
If there is any signs of black death go ahead and flush the a/c system completely.
If you need help doing it post here, or PM me and I will be more than happy to walk you through it. A phone call may be in order because of all the steps. If you don't do it right you probably will be doing it again. The low quality remanufactured compressors made today need every chance they can get. In the old days they were more forgiving, but sadly those days are gone.
Whatever you end up doing pour the old oil out of the old component(s) and measure it. Add the same amount of NEW oil to the new parts. Too much oil is worse than not quite enough. It will be easier to use the type of oil you pour in rather than the kind that comes pressurized. Be careful with the oil in the suction side of the compressor or you will damage it.
The final step is to pull a good vacuum down to 30hg for at least 30-45 minutes (you cant do it too long). This will remove any air in the system butt more importantly it will allow any moisture to "boil" out. If you don't have a pump, one of the air operated $9.99 Harbor Freight ones will do nicely.
You can get by just changing the compressor, but if you do it right you will not have to mess with it again for a long time. The air will be colder too. There is nothing worse than the A/C going out on a hot day.
If I can be of any more help please post here, or PM me. I am more than glad to help.

Now someone help me with my idle problem posted below
Best,
Justin