HVAC system is not blowing air... failed when driving, now EATC Code 52 | Ford Explorer Forums - Serious Explorations

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HVAC system is not blowing air... failed when driving, now EATC Code 52


Well-Known Member
March 13, 2016
Reaction score
City, State
Western US
Year, Model & Trim Level
'00 Explorer EB 4SOHC RWD
I turned on the AC one early-morning and after driving for 2 minutes, the fan stopped blowing. Ran the EATC self check and got code 52. (A/C solar radiation sensor circuit short to ground)

2000 Explorer Eddie Bauer RWD with EATC

I have not begun to troubleshot past the EATC self check yet as I think its the blower motor resister however since there are many relays and fuses for the system I better post here first.

Will ask for advice to begin diagnosing this issue,

1.The fan control never seemed to work right. Most of the time it would only be blowing out high no matter the dial setting. This was probably the case for 10 years now.

2.last week I just replaced some gears in the blend door actuator motor assembly as one gear had broken splines. I had the actuator out and used the AC for maybe a week while I sourced the gear.

3.seems that the EATC system is beginning to have vacuum issues now for 9 months. Under loads (uphill) mostly in cruise (but happens when not using cruise too) the ventilation changes up to defrost. Typically it switches back to say panel vents when the load is back down to normal again. I did replace some vacuum lines (junk yard sourced) as I broke both going to the HVAC vacuum reservoir about 6 months ago when I took off the wheel well cover. I just replaced the Heater Control Valve and hoses (leak) and the stupid updated motorcraft valve assembly does not have the same vacuum connector as the old... fits but is not as tight as the original.

4.typically in low humidity areas but when it failed I was in a high humid area (morning dew) and driving on road next to the ocean.

5.Ac compressor seems to cycle due to change in RPM at idle(but haven't lifted the hood to watch the clutch). . Rear fan works in the center console.

I thought to first look over the fuses (in my mind, haven't done in reality yet).
I googled the fuse boxes and see only one mini blade fuse but that is for the rear fan.
In the main fuse/relay box there are about 3 that are related to the system.
Being that the resister is so buried down, not sure if I can check for power there or at motor without disassembly.

SO what would be the best way to start and proceed?

thanks in advance.

1. My guess is that you have a problem in your blower motor speed control module and that's what causing you to only have one speed and very possibly your EATC error code 52. It is also possible that your blower motor is wearing out, though I think this is less likely. It's not unusual for the blower control modules to fail. For this reason, junk yard modules are not a good replacement, though new modules are rather expensive.

2. Find and fix your vacuum leak. It's probably not the EATC unit itself. A tiny (and I mean tiny) vac leak will cause the system to default to the defroster vents when the engine isn't producing much vacuum (like when the engine is under a load). If the vacuum line on the your new heater control valve is loose, that's enough to cause a problem. On my first Explorer someone had plugged an unused rubber vacuum "T" port with a small screw. This created a small vac leak, which caused my air direction to default to the defroster vents when climbing a steep hill near my home. Removing the "T" and adding a splice fixed my problem.

Well I finally scored a resistor or whatever it’s called (blower motor resistor) for the EATC system from a 98 limited v8 at the junk yard. First trip, there where only manual systems in like 25 explorers. Second trip but without tools at a yard far outside town had 2 but again it was just to see and would need to return with tools. Third trip in the cool, early morning at the closer yard there finally was this 98 limited with EATC.

Well the donor explorer was impacted on the front right tire well and when I removed the cruise and coolant/wwf reservoirs I found the unit out as much of the casing and well covers all cracked from the accident it had. The Heat shrink had very little damage, one upper line of say the ten was pushed towards another line. The casing and circuit board appeared ok. But the unit had no corrosion or appearance of being in a high humid area such that my original one appeared to have (15 years near the SoCal coast).

Anyway, installed it and now have blower motor operation. Now have full control of fan levels from low to middle to high. Seems at least four settings or more. One big difference though is that my original one hardly ever worked properly for speed control and default at full max high which was lots more air flow than what this used part is delivering. I would say the new part is only delivering out 75% of the volume/speed of the old, bad part had been.

I was about to give up on getting a used part. Most dealers wanted 170+tax for this part but one dealer here had it for 122+tax (thru Ford parts). I still wanted to prove it was this part before buying new... happy to find a good for now unit.

There was a video on youtube that should the bench testing of the manual AC system. It would be nice to have had the info to ohm test the EATC version.

My old one had the part number sticker of

which is what Ford parts will find as Part #: YH1835 (19E624) and call it "Control"
Usage: Front, 1998 - 2001, Explorer, w/ Auto Temp Control
Section: Ford Motorcraft AC200

I don't know why Rock Auto is saying the part number is YH1835 {#XL2Z19E624AA}
notice the ending AB vs AA (rock auto) yet rockauto pictures show it as AB. Sells there for 90+shipping.

My old one was interesting because it looked like someone had written the letter H on the sticker. Again, I cant remember that it ever worked properly for all speeds since I bought it at 90k miles in 2008. The used one from the 98 was missing the sticker, but looked original. Mine had "mexico" on it but the 98 had MEX, a few other number differences on the circuit board between the two. Paid like $6 at the junk yard with a 30 day warranty. If I ever go out there again, I surely would try to pick another one up that is from a 2000 or 2001 because its cheap and here in the arid, dry SW USA they are probably in better condition than most other areas like SoCal.