So I’ll start in saying that I’m pretty mechanically inclined and can tackle most jobs without fear. But air conditioning is something that really kind of evades me. I understand the very basics but troubleshooting does not come naturally to me.

Last week my AC started to blow warm/ambient air. In Texas it’s still in the 70s the last week or so. I noticed my blower wasn’t pushing air quite like it used to so I figured cabin air filter. It was pretty clean, I changed it anyway. What was also happening was I noticed the AC wasn’t freezing me out like it used to. I usually set the dial to 68-70 and fan at 2-3 speed for normal cruising.

I took the truck to a shop that I trust but haven’t been in a number of years. I’ve got a newer truck that hasn’t needed service, so it’s probably been 7 years or more. The technician hooked up the AC machine and showed me the gauges when he started the truck and I kept an eye when he started the AC. Both high and low side pressures were way too high. This is the factory refrigerant fill. Pressures were 400/high and 50-70/low.

The tech suggested the fan clutch was at fault and not pulling air to cool the condenser. That made sense. I asked a few questions to help me understand and he was pretty adamant that was the issue. He quoted me $850 for service.

So this weekend I picked up a fan clutch from Advance and went to town. Replaced it only to find this one was locked up and the clutch was fully engaged all the time. AC was still not as cold as it should be, so that helped me realize the fan clutch might not be the issue if it’s constantly running. I pulled the Advance clutch and replaced it with a Napa OEM fan clutch. It actually said Ford on it.

The Napa clutch was good, no fan howling, cycled off properly, etc. However, the AC issue was still not fixed. Some mixed Highway/city driving had the AC temp climbing back to ambient along the 15-20 minute drive. At that point I completely ruled out the fan clutch. So I ripped out the Napa and reinstalled my original fan clutch.

After $600 in experimental parts I’m a bit pissed at the shop for being dead set on a fan clutch, yet very thankful I didn’t green light them for an $850 incorrect service.

So now I’m lost as to what is causing my issue. It’s a 2017, I have a hard time believing substantial parts like fan clutches and evaporators are failing in under 5 years. Most vehicles go decades on factory AC components with lesser quality parts.

I need some ideas. Next step is checking the drain tomorrow morning. Although when I’ve been running the AC I’ve still been seeing a puddle of water under the passenger side.

If nothing else, it will go to the Ford house.

 

I can't help with the diagnosis but I wouldn't put that much faith in the parts themselves. There have been plenty of posts describing early fan clutch failures, evaporator failures, and my own truck had the compressor fail with less than 10k miles.

 

Fair point but after 3 fan clutches I can rule that out. Compressor? That’s another issue. It does engage, I’ve watched it, and does disengage assuming due to high pressure cutoff.

You’re right though, anything can happen.

 

blend doors stuck in heat mode?
Loss of refrigerant?

 

1. No because it cools first then gradually warms up.
2. No because the refrigerant generates pressure when the compressor is running.

I’m thinking it’s something after the compressor like the condenser or expansion valve. But I am not an AC expert.

 

None of those items I listed were intended to be a diagnosis or even a guess on my part, only to say that yes, the A/C components can and do sometimes fail early on these trucks.

I will be interested to see what the problem turns out to be.

 

Do you have a gauge set? You will need those to assist in the diagnostic. You want to check for airflow through the condenser. It never hurts to do a good cleaning of the condenser even if it's not blocked by moose hair. So, clean the condenser and check pressures. If they are still high, you can run the system and run water through the condenser fins. You should see high and low side drop significantly. The tech working on your system should have done that as it is a good indicator of insufficient heat transfer in the condenser. If the condenser is clean and you have good airflow, and pressure drops from water, then something is going on with the condenser. I don't know what that would be. There are a lot of very good online sites that can help with diagnosing automotive A/C. Here, things are too general to find that level of expertise.

 

This system has never had an issue, this is the first? Never had it touched whatsoever? That high side at 400 sounds like a blockage if the pressure spiked like that right away when the compressor kicked on. The tech is saying not enough air which you could see by blowing a big fan and seeing if the pressure comes down. Hard to mess around on your own without gauges.

 

Sounds like a TXV (thermal expansion valve) issue. The TXV regulates the pressure differential between the high and low side of the system. The reduced air flow was most likely caused by the evaporator freezing up.

 

Get a diagnosis and then get pissed when you attempt the repair yourself without fixing it? hahahaha.

 

A plugged txv/orifice will do it. Usually you'll have a spike on the high side with lower than usual on the low side. It can also cause icing as well. A pressure check and comparing line temperatures will confirm it. Usually if it's plugged, it's from a crappy install or a failing compressor.

It could also be a plugged drier. Anything with a restriction can cause it.. are any lines pinched?

I did res hvac for 12 years till I left the trade. I've repaired my own vehicles without an issue. Theyre very simple systems, but it is impossible to diagnose without a gauge set and some temp probes. Automotive ac's are even more temperamental since there are so many variables and the charge is so little. A couple ounces +/- can make a big difference...

Honestly if you don't know about the system, take it to someone who does. Even if I walked you thru it there are too many variables and too many little steps to take to do it correctly.. The guy that said airflow was an issue obviously doesn't have a clue because you can check airflow (and even running water over the condenser will "simulate" more airflow and rule that out)

Any time you open the system you'll need gauges,a scale, a vac pump,, and preferably nitrogen to pressure test the system. You'll also need the correct oil to add in when replacing a component to replenish what was lost...

 

If the evap coil is freezing up, its usually under charged.

I run my AC all the time, it keeps oils flowing and seals wet..If you only se your AC in warm to hot weather, there will be a chance seals dry up and create a leak or loss of refrigerant....we can all throw darts and guess. I would suggest a reputable AC shop or bite the bullet and go to the dealer.

Good Luck, keep us posted

 

Thanks for all the info. I'll get a gauge set today and take some cold readings. I'll drive my other truck all day so I get a true feeling of how much refrigerant is actually in it.
I'll update when I find a solution.

 

Remember readings with the truck off are meaningless. Have the ac om, windows down and blower full blast. Take note of line Temps (taken with a line clamp or similar, not a temp gun) outside wet bulb and dry bulb Temps, air vent Temps. Check qt idle and increased rpms

Again, the point and shoot temp guns won't work for temp measuremnts. You need accurate measurements to be meaningful.

 

Sometimes A/C expertise is worth the money.