1999 F150 A/C Not Working

Automotive
#1

I recently picked up a '99 F150 which was owned by Paris, TX as a fleet vehicle up until very recently. Currently, an among other not working things, the A/C does not blow cold – as well as the blower occasionally and briefly cutting out. After speaking to Sam and watching a few YouTube videos including

I popped the hood and turned on the A/C and took a look at the compressor. I can see it cycle through the clutch engaging for about 2 seconds and then disengaging for about 6 seconds. After praying to the internet, the AI Gods bestowed upon me the knowledge that this could be caused by low pressure/refrigerant.

The truck takes 33oz of R-134a, which at O’Reilly is about $40 for three cans of Chemours R134a Refrigerant With Valve 12 Ounce - R134A-12V (just the refrigerant) vs around $120 for two cans of A/C Pro R134a Ultra Synthetic Refrigerant Kit 20 Ounce - ACP100V (includes a valve and gauge).

This being said, and as I don’t know the history of what’s been done to the A/C system in the past, I’d like to follow the steps in ChrisFix’s How to Properly Recharge Your AC System. This will clear out any air and moisture in the system – as well as save me about $80 which will pay for a good portion of the break pads and rotors that need replacing. Aside from the refrigerant itself, the video calls for:

  • Manifold gauges
  • Vacuum pump
  • Nozzle to tap the refrigerant
  • AC Vent thermometer

I’ll be in today around lunch to replace some broken studs on my drivers side front wheel and if I can find everything I’ll give it a shot and share how it goes.

#2

Sounds like a fun project - I’d love to learn how to do this myself. I know that auto parts stores carry some loaner versions of the tools if the makerspace doesn’t - the O’Reilly’s I went to the other day said it would take a day to get them in.

Let me know how it goes and if you find the tools!

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#3

Well. You might want to find the leak. It does suck to have the unknown if not knowing when refrigerant was put in last. This would kinda help filter out what size leak you are looking for. Personally I’d stay away from any refrigerant that has any oil in it or for that matter dye. Excessive oil will cause oil logging in the evaporator thus causing lower pressure readings as well as lower heat transfer.

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#4

@TBJK - Considering the condition of the rest of the truck, it’s a pretty safe bet that there is a leak, but right now I’m not sure how I’d find it – unless the previous refrigerant that has long since leaked out had dye in it and there is still some residue indicating where it leaked out from. Staying away from refrigerant with oil and dye seems to be the general consensus. However, the only way I’ve seen to check for leaks is with dye.

I’m guessing that the system needs to be pressurized with refrigerant before any dye will leak out anyway, though it would be great to fix any leaks before I pump $50 into the system.

@garrethw - I found a manifold gauge, but it looks like it is way off calibration (see picture). Not sure if it will work or not.

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I saw Sam briefly while I was finishing up putting in the new studs and he said we do have a vacuum pump, but I couldn’t find it.

I checked out the O’Reilly rental policy and here is how they say it works:

To rent tools from your local O’Reilly Auto Parts, simply purchase the auto parts you need and put down a deposit on the rental tool. Return the rental tool in its original condition and receive a full refund when you bring it back. Need the same rental tool for another repair? Come pick it up again, or feel free to just keep the rental tool once you’ve paid your deposit. The deposit is also the purchase price, so if you decide you’ll use the tool often enough, you can keep it and add it to your collection. It’s that easy.

The gauge set is $130 and the pump is $170. The question is, once they’re used to recharge my A/C system, are they still in “original” enough condition to get my deposit back?

#5

This is a question for O’Reillys, but I think the answer is yes.

#6

I’m going to head over to the one on Josey and ask.

#7

The gauges aren’t necessarily off. The valves that clip onto the system will hold pressure. They have a style of schrader on them. I can lend you my leak detector when I am here. It will detect 1 gram a year leak rate.

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#8

@TBJK - Thank you so much, that would be amazing! I’ll be back by Sunday afternoon, does that work for you?

@ozindfw - I stopped by O’Reilly and you are correct. They have loaner units and they are all pretty well used!

#9

Damn near any day except for Sundays. My weekends are normally for my family, committee meetings or special project are the only exceptions in most cases.

#10

Thanks for paving the way on this @Roburlion and for sharing info - I have a new AC compressor to fit on my Ford, and will have to do all the filling and vacuuming soon.

#11

I have a 2004 Expedition and was having issues with the blower constantly switching to windshield defrost.

Turned out to be a disintegrated vacuum hose.

Your blower cutting out might be that the blower is switching destinations like mine was.

Once you find the hose it is pretty easy to replace.

I went to O’Reillys for refrigerant initially and asked about how to check the current pressure. Their suggestion was to purchase a refill canister and carefully use the built in gauge (without cutting the ziptie on the pipe), then return the refrigerant unused for a refund :slight_smile:

In my case the refrigerant was fine, which then led me to finding out about the vacuum pipe. Mine was completely crumbled !!!

Back at O’Reillys I told them I needed about 12" pipe and they gave me the end of roll piece that was more than I needed, for free !! I felt a little guilty so filled up on washer fluid too :slight_smile:

#12

This is a dumb question - how do I safely extract the existing refrigerant / oil out before taking the compressor off?

Do I just connect a vacuum pump to it, and then the refrigerant gets collected safely somewhere like a ghost in a ghostbusters trap?

#13

The legal way is to recover the refrigerant into a tank using a recovery machine. Then putting the refrigerant back in.

#14

If no AC service history, Its best to change all the o rings at every connection point you can find including:

the compressor seals

the orifice tube

both high and low shrader valves including their caps
and the pressure switch if any.

If your compressor has a control valve, the o-rings on that may need replacing too.
It will save you time in the long run because if one is bad, then another is sure to follow in the coming years.
This is because with a 25 year old vehicle the o-rings degrade or wear out over time there could be several leaks anyway. Also, Ive discovered on my vehicle that it will hold a vacuum for 45 min and not show leakage. Metal contracts when its cold, the micro leaks occurred when driving and the newly added pressure was able to seep out.

When you hook up the gauges to the car and run the vacuum, it should drop to zero and stay there if you shut off the vacuum; providing the hoses and its connection points are air tight as well.

But if you really want to do the dye method, one can is enough to kick on the compressor, then drive with the ac on high as it works its way through the system.

#15

I will add, if you do change the o-rings, buy Viton o-rings. There is an O-ring supply shop called HD-Distributors off Round Table in Dallas. Standard O-rings will not last as long as the Viton will. They are more expensive though. Let’s say the standard is .45 cents, the Viton will be like 2.50

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