Automotive Air Conditioning Information Forum

Thanks for all of that info Bohica! Really helpful! One thing I still fail to understand is that if the fan clutch was the problem, why will I still not be able to achieve lower outlet temperatures when rolling down the highway? I can feel air being pulled from the front side of the condenser at idle. The condenser definitely isn't hot to the touch-- not sure if it is expected to be hot if it's not getting enough airflow or not, but it's definitely not hot. The engine coolant temps are also normal.... the engine never gets overly warm nor hit. I'm just trying to save the headache and expense of replacing the fan clutch if that's not the problem. Here is a video I took earlier of reaching under the engine cover and spinning the fan blades by hand after 40 minutes of driving today. There is definitely resistance... it's not turning loosely. Not sure if it's perhaps has too much resistance, but maybe you all can tell from the video:

https://www.youtube.com/watch?v=oE-ysJAocs8

Also the door that seems to be of issue is the one that simply changes which outlet(s) get airflow... the one that cycles between the main dash vents, the floor, and the defrost vents. Would that one also be affiliated with a passage that would allow warmer air into the mix? I would have that that would be a separated blend door.

I'll definitely grab an AllData account, I used to have one. Actually, I have the Ford PC/ED (troubleshooting) CD for my vehicle, maybe I'll check to see if it covers homing the servos first. I did see a video of a guy with a 2006 F-150 that had foam that separate from a blend door get stuck in the blend door and not let the door close fully... wondering if I might have something similar going on.

Thanks again for the help!

Get the vehicle warmed up, have someone turn off the engine while you are looking at the fan. If the blade still spins when the engine is off, replace the clutch. You should be able to find a YouTube video on testing the fan clutch.

Fan clutches wear. Sure the fan still spins. This is from the old site, and explains in detail:

http://www.autoacforum.com/messageview. ... adid=10772

Complicated systems can have more than one failure point. The fan issue reduces loop efficiency, mostly below 35 mph. But you have an air door that is not behaving properly - what is the possibility that the blend door is not closing completely as well?

You would not believe the things we have found in evaporator cases. You could have debris blocking some surface area.

Have you calibrated the thermometer you are checking the vent temps with? Glass of water & ice - does it read 32f?

Thanks for the responses again! So I went out a little bit ago today with my phone to video tape the cooling fan. The engine was still nice and hot (not hotter than it should be, just hot) from the drive I just got back from, so I started a video on my phone and then remote started the car. The fan is definitely not loud out at all, as you can tell, which seems to be a sign that the fan clutch is bad, but this was to see what happened when I would shut the engine off. So I let the engine run for a few seconds, and shut the engine back off at the end of this video:

https://www.youtube.com/watch?v=TVpg8AFhjlg

You can see the bolts on the A/C compressor clutch spinning around, and once the engine comes to a complete stop after shutting it off (you can see one of the bolts down load on the A/C compress stop right in view), the fan continues spinning for approximately another 2 seconds. I hadn't seen anywhere else that this is a true indicator of a bad fan clutch, but if what you said is definitely true then it is definitely bad.

Thanks for the link by the way Bohica. I was trying to find YouTube videos on testing fan clutches prior to my last post, and could only come up with people showing worn clutches spinning loosely as an example. The lack of noise coming from my fan, especially on startup, I suppose suggests the fan clutch is bad.

Rather than going through the various methods of testing the speed of the fan, not knowing the history of my current fan clutch, I'm going to assume it is the original unit. I already ordered a new fan clutch and fan assembly (probably didn't really need the fan assembly itself, but I've replaced everything behind the timing covers [cam phasers, timing chain, oil pump, timing chain guides and tensioners, etc] as well as all of the accessories [water pump, alternator, A/C compressor, power steering pump, idler pulleys, tensioner and pulley, belt, etc] so I'll just do the new fan assembly too) so should be able to replace that this-coming weekend after the parts get in.

I figure I'll start with the the fan clutch and fan and see where that takes me. Beats tearing apart the dash for possibly nor reason. Worst that can happen is I have $150 in a new fan clutch and fan, and still have to tear the dash apart to check the issues with doors and/or actuators.

I did take a look at the side of the evaporator that faces the blower fan. I went into the plenum through the blower motor control unit with my borescope and saw absolutely no debris on the evaporator nor in the rest of that side of the plenum. I was surprised to see that, due to this vehicle not having a cabin air filter on it (not that it is missing, it just wasn't manufactured for one), but relieved at the same time. Maybe the previous owners were good at keeping the recirc mode on.

I have not calibrated the thermometer I'm using, but I compared it with my buddy's similar digital thermometer and both units were within .2 degrees of each other at almost any given time. I then compared mine to a standard thermometer at their really all giving the same results. I can definitely tell that when I feel the air has gotten as cold as it will, it is still not as cold as I know it should be, then I turn on the thermometer to confirm and it's maxed out at 45 to 47 degrees every time. 45 is cold, don't get me wrong, but not good enough on those really hot days where the truck struggles to put out cool air at low speeds.

Thanks again so much for the help everyone... I'll keep you all posted once I replace the fan clutch this weekend!

-Andrew

I've had my '88 Mazda truck since 1994, and I've changed the fan clutch about every 6 years (Hayden lifetime).

Thanks for the info Cusser! Honestly, this is the first vehicle I've had with a fan clutch, since my first vehicle in 1999 when I was in high school, which was a 1987 Dodge Raider haha. Have owned many vehicles since, but all have had electric fans up until this one. Never occurred to me that a fan clutch could be bad without being seized up nor spinning freely. Learn something new every day. Sure beats paying a mechanic to do all of my work though

You will hear the difference on the first cold start after install.

Consider the P/T curve. With 250 psi, the liquid is 147f. With 200 psi, the liquid is 131f

Every single thing in the system has an effect. A little too much oil, a slight undercharge because of poor condenser performance, etc. Many faults mask other faults.

You seem to be restoring this vehicle to OEM - new cam phasers etc. Replacing the plastic fan was a good call, years+miles add up on polymers.

Keep us posted.

Just viewed your video. Loks like fan clutch to me.

bohica2xo wrote:You will hear the difference on the first cold start after install.

Consider the P/T curve. With 250 psi, the liquid is 147f. With 200 psi, the liquid is 131f

Every single thing in the system has an effect. A little too much oil, a slight undercharge because of poor condenser performance, etc. Many faults mask other faults.

You seem to be restoring this vehicle to OEM - new cam phasers etc. Replacing the plastic fan was a good call, years+miles add up on polymers.

Keep us posted.

Dougflas wrote:Just viewed your video. Loks like fan clutch to me.

Yes Sir, I was needing to replace the cam phasers... and no sense, in my mind, in not replacing everything else I could that had mileage on it, while I was in there. Nothing like having a bunch of new parts and not having to tear back into things later to replace components you could have replaced last time you were in there

So sadly, installing the new fan clutch and plastic fan didn't really change anything. The fan actually spins far for a couple seconds longer after shutting the engine off than my last original one I removed, and it's definitely no louder. It's the Motorcraft fan clutch and plastic fan... not aftermarket. I might be seeing a very small improvement in maintaining cool while at idle in warm weather, but I'll need a few more days to see if what I noticed is consistent on hotter days. Just before changing the fan clutch we had an 80 degree day and noticed the vent temps increase about 8-10 degrees (to about 55-57 degrees Fahrenheit) when I came to very slow-moving traffic, after I had just gotten the vent temps down to around 47 degrees minutes prior while I was cruising down the highway. Anyhow, no hard feelings whatsoever to those who suggested the fan clutch. It was worth replacing since I replaced absolutely everything else on the front of the engine, and was worth seeing if that was the fix before tearing into the dash. Process of elimination.

I have noticed that my idle is really low, but seems to be normal for a lot of these 3-valve 5.4 engines. I'm at right about 550 RPM at idle, while in gear. That's with or without the A/C on. The intact tracts are very clean on the engine. I've cleaned the MAF with MAF/electronics cleaner, and I even have a brand new Motorcraft throttle body on it (old one was very clean but I broke the throttle stop pin on it when I was diagnosing a TPS issue last year). Air filter is a brand new AIRAID oil-free filter. Had the same issue with the previous paper filter too. If I put the vehicle in park, the idle raises around 200-ish RPM, and the air definitely gets around 3 degrees cooler than idling in gear. So I need to do something to get the idle speed up, but that's probably going to involve buying a handheld tuner. Regardless of that problem, there's still the fact that I can't get below 45 degrees with the front and rear A/C set to the coldest setting, max fan speed, recirculate mode on, while barreling down the highway for an infinite amount of time. I could literally drive 2 hours, and get the cabin pretty chilly, but never see colder than 45 degrees coming out the vents.

Before I go and tear the dash out this weekend, is there anything else you guys can think of that I can test? I have a new Motorcraft heater valve that I'm quite certain is blocking coolant flow with the A/C on, but I can certainly try to pinch the hose to the heater core completely with some vice grips and a rag (so I don't damage the rubber hose) or something. That should tell me if the heat/cool blend door is not closing all the way I suppose, right? I would assume that if pinching the heater core line off gives me cooler vent temps then either the heater valve isn't closing all the way, or the blend door isn't closing all the way?

If I do end up tearing into the evaporator plenum this weekend (removing the dash... ugh) I'll definitely have a new Motorcraft evaporator to install once I have the system evacuated. At this point I'm pretty certain I don't have a refrigerant leak, because now around 2 months since the last recharge I'm still able to get the same 45 degrees out of the vents at times. But what is also weird is that I took a 5 minute drive up the highway after installing the new fan clutch and got 45 degrees coming out of the vents going one way, then I did a u-turn on the highway and could only get 48 degrees all the way back. That's doing the same speed, with the same load (just barely any throttle in 6th gear), etc.

Any other suggestions?? I'm open to ideas still!

Those that read my prior posts within this thread might recall that when I did a vacuum check, followed by a pressure check (with nitrogen), the system wasn't holding. I actually did several more vacuum checks after the first pressure check, and could see a decrease in vacuum after just several minutes. This was all done using various gauges (analog gauges manifold set, digital gauges manifold set, my RobinAir A/C machine gauges)... so I think I can eliminate the gauges/manifolds from being the problem. So I also wonder if this lack of ability to maintain pressure or vacuum was because the expansion valves were closed, but maybe bleeding a very small amount (of nitrogen or air) through them, which is perhaps to be expected?? Or does hooking up vacuum and gauges to both the high and the low pressure ports on the car allow access to both sides of the TXV's, ruling out anything bleeding through the TXV's and causing the system to look like it wasn't holding??

The fact that 2 months since the last recharge is still getting me the same 45 degrees coming out of the vents at times makes me really wonder if anything was ever really leaking to the atmosphere??? Thanks again everyone!!!!!!