Hi all!! First Post!!!

Alright, I'm 17, with good mechanical ability. I am more familiar with small engines, but my 99 F250 was in need of an a/c compressor, so I figured what the heck, and started into it. I bought a compressor, bought r134, and went to work. I got the old compressor out, and put the new one in, and I'm stuck there. I was reading on the net this morning about the compressor needing to be filled with oil, and that I probably needed to clean my filter as it is probably dirty from the old compressor going bad. So, my question is, do I just pour the refrigerant oil directly into the compressor? How much should I use? Where is the "filter" or "screen" that I should be cleaning? Also, can someone explain/show me a picture of where the low side pressure connector is so I know where to put the new refrigerant in? I bought a bottle of the do it yourself stuff at auto zone, is that enough? Sorry for writing you all a book, I'm just a little lost and knew that I could get some help on here from you experts.

 

Hi cantwait. Welcome to the forum. I can certainly understand your enthusiasm for wanting to tear into this problem yourself. I was probably the same way at your age. Unfortunately, good mechanical ability does not necessarily equal the detailed HVAC knowledge or experience required for this job. A/C systems, though seemingly simple, are actually quite complex. All of the components need to be in perfect balance or the system will fail.

For example, how did you determine the first compressor needed to be replaced? Smoked windings, undercharged, acid in the system, etc? There are numerous potential causes and the underlying condition for each cause must first be corrected before installing the new compressor - otherwise you are simply wasting time and money.

When a compressor fails, the breakdown of the internal components often contaminates the oil, which also needs to be removed from the system or the new compressor will also fail in rather short order. The oil is not confined to the compressor, it is dissolved in the refrigerant and circulates throughout the system, Therefore the entire system needs to be flushed and evacuated before new refrigerant and oil is added following a compressor swap. This requires special tools and equipmemt for refrigerant recovery and charging, as well as a high quality vacuum pump to remove all of the air and moisture prior to recharging. Even the slightest amount of water vapor left in the system will also turn the oil acidic and cause the new compressor to fail.

I think you get the picture on what this job entails.

You may want to read up here for example:

Auto Air Conditioning - Replacing your auto A/C compressor

btw, I used to work in the HVAC business for 10 years.

 

Great reply Grumpy and welcome to you cantwait. At that age I too sometimes tried to tackle things that maybe I did not know enough about, I learned a lot that way...just sometimes a little expensive. Anyway, once again great post Grumpy, reps to you.

-Glenn

 

I second what Grumpy Moose said, you can do a lots of things on the truck your self,
but for some things you need proper equipment.
No way around it.

 

Bad news: More than likely, your A/C system needed nothing more than the compressor head space adjusted, which is a fairly common problem.

 

Thanks for all the help guys, and after a little more research I have decided to just take the truck to a mechanic and let him vacuum out the system and recharge it with oil and freon. I have everything put back together and its running again.

Some background on the truck......... Blew the motor at 120k miles, and we bought a used one with 80k on it. The truck sat for about a year and finally we got around to getting the motor installed. When the mechanic put the motor in, he attempted to charge the a/c system with freon and oil, but the compressor had already failed from sitting so long. He told us that everything was in good condition in the system other than the compressor. I have driven the truck for going on 2 years now with no air, and our 90+ degree temps lately have inspired me to get it fixed.

Thanks for the replies guys. Lots of good info!

 

we have probably more truck talent onthis site than anywhere else. just ask and someone knows the answer.

 

Now for more questions!! The truck also seems to "jump" or "miss" at low rpms, and mainly only in overdrive. If I am going up a hill, and the truck is in OD, just crusing, it will jump or miss badly, shaking the truck. But if going up the said hill I let off get on it a little harder to get it into higher rpms (and the gear below OD, 3rd?) and its turning around 2000-2200 rpms, you can feel it hiccup once maybe twice but not enough to shake the truck, or near as violently as when at lower rpm in OD. I've been told from a few that it is probably the coil pack and/or spark plugs. Would this be a cause? It idles a little rough also. Thanks for all the help!

 

There can be a host of reasons for this. Check all your obvious items first. Can i assume you have kept it in tune with plugs/fuel filter? Have you checked for codes? How long has it been doing it? Has it gotten worse as time goes on?

 

Its been a long while on the new plugs, and fuel filter I honestly couldn't tell you. Codes? Don't really know to check those. It has been doing it for a year, and has worsened over time some but not really drastically. It seems to do it worse when the truck is hot or when the air outside is humid.

 

Your hiccup could be a lot of things. Fuel delivery, spark, transmission, electronics, exhaust....the list is endless.

I had a 1995 F-150 that would shudder when driving down the road, usually at the same spot on my route, climbing a hill and going over a rough patch of road. After trying a few things to find the issue. After about 6 months of this I replaced the battery (because it was getting old) and the problem went away. Could it have been the battery?

Start by having the truck scanned to see if there are any error codes. Most chain auto parts stores will do this for free. It is helpful if the scanner can read pending codes, most of the free scans won't have this.

 

Well the mechanic that finished the job for me drove my truck from my Dad's work to his shop, and we had him take a quick check. He said he is 99.9% that it is the plugs/coil pack. So good news there!!

 

Welcome to the forum! Yes, you put the PAG oil directly into the compressor, rotating it slightly every so often as you pour. To recharge the R-134A you will need the proper manifold. When you do refill, here are a few tips for you. Do NOT open the red line, otherwise you can blow the can up. Also, warm the can with hot water (not boiling) before you charge. This will pressurize the can and force 134A into the system. The compressor will not kick in to "suck" the R134A in until it reaches a certain pressure threshold, and forcing the refrigerant will allow enough R134 to enter the system until the compressor kicks in. Good luck!