need mustang help

RodneyWright · **Posted:** Mon May 04, 2015 8:00 pm

So I can use an assist here please. Issue is the mustang runs hot w/ out the AC on.

Issues are...

> temp climbs up to 220-230 w/ out the AC on
> fan runs fine when the AC is on.
> fan will not trip when AC is off
> did smell something on the way home from NCCAR but didn't notice the gauge at that time, just didn't pay attention I guess.
> can't find any burned wires
> no bad fuses I can find

I've replace the fan switch which is conveniently place under the intake manifold. New ford sensor is in place and that has not corrected the problem. I also replaced the t-stat. Again, once I run the car sans AC and the temp starts to spike, flip the AC on and the fan runs and temps drop. While I can drive the car w/ the AC on, it's not my favorite thing to do and pretty much sucks when you autox it. We have an autox in 2 weeks and CMP in 4, so I'd like to get this sorted out.

Seems to be some misguided info on some of the forums I visit. I can use some clear and intelligent heads to help me chase down the issue.

Jordan Normark · **Posted:** Mon May 04, 2015 10:10 pm

Man, Talk about Fix Or Repair Daily. With the fan temp sensor under the manifold and thus located high on the engine; is there any chance there is air in the cooling system preventing coolant from contacting that sensor? You probably lost some when you changed the sensor plus you mentioned smelling something, I assume that something was antifreeze.

RodneyWright · **Posted:** Mon May 04, 2015 10:59 pm

Jordan Normark wrote:

Man, Talk about Fix Or Repair Daily. With the fan temp sensor under the manifold and thus located high on the engine; is there any chance there is air in the cooling system preventing coolant from contacting that sensor? You probably lost some when you changed the sensor plus you mentioned smelling something, I assume that something was antifreeze.

Yeah, this ford is living up to its F.O.R.D. reputation. The fan sensor is in a non-water jacket location in the head. I think what I smelled was part of the fuse box melting. I'll know more tomorrow when I get it back in the garage. Finally got the BMW in driving condition and I was able to get the mustang back together after replacing the fan sending unit only to find that wasn't my fix.

After some more digging on the interwebs, it seems the S197 mustang is prone to losing either the high speed or low speed fan relay due to an over amp draw. Seems for me I've lost my low speed fan. Sat in the car and turned it on and watched the gauge. It usually sits right around 190 on the gauge. It kept creeping past that until it got to a little over 220 then the high speed fan kicked on and the temps dropped quickly. Funny thing is the factory idiot gauge just sat there in the same position giving NO indication of anything wrong. I despise dumb gauges, pointless.

Anyway, going to pull the neg terminal on the battery and then pull the fuse box apart. This, I have found out, is a 2 piece fuse box. The "fused" section separates from the main connectors. This is where I think my situation lies. Some folks have re-routed a new 10gauge wire and new 40 amp relay to make a separate circuit to the fan. Haven't found any pics of that yet nor do I know which wires I need to cut for the re-route.

Issue now is do I need a new fan? Need to test the current draw on the fan. Not sure what the normal draw rate and start up rates are on the fan. The car is only 6 years old w/ less than 80k on it. I'd expect better.

BenjaminGuardiola · **Joined:** Wed May 14, 2014 8:31 am **Posts:** 84

I hope this isn't a dumb suggestion.

When I was heavy into rockcrawling, it was common practice to wire both fans into one switch and place it in the cabin. Flip a switch and both fans would run on high. Flip it off to go through deep water. We ran all day at such low speeds there was not enough air flow through the radiators so running both fans on high helped keep temps down. If you are having to dig into the electrical anyway, might be a good time to run parallel.

Michael Westerfield · **Posted:** Tue May 05, 2015 8:27 am

What does the stock gauge say? Didn't you just put gauges in it?

I remember my 08' ran hotter than other cars I've owned. I remember seeing 220-230 at an autocross and that was more or less normal. Are you sure you have a problem?

Vincent Keene · **Posted:** Tue May 05, 2015 8:31 am

Michael Westerfield wrote:

I remember my 08' ran hotter than other cars I've owned. I remember seeing 220-230 at an autocross and that was more or less normal. Are you sure you have a problem?

Mine runs 220-230 on track also.

FYI, the hi/lo fans settings can be altered via your handheld tuner.

RodneyWright · **Posted:** Tue May 05, 2015 10:49 am

@ VK and Michael.... Yes, I'll see higher temps when I'm beating on the car, but I was sitting in traffic when this first occurred. As mentioned, the new fan sending unit didn't change anything. I was able to look at the fuse box, but didn't find any issues, which is good. I expected to find this....

http://www.s197forum.com/forum/showthre ... unning+hot

I guess my next attempt at a fix is to replace the low speed relay. This is the only thing that makes sense since the fan itself works, the fan sensor works and the high speed relay works. Part is coming in this afternoon.

BTW, I'm finding the new Crossroads ford on hiway 401 (was Don Jenkins) is fairly worthless in regard to parts. They didn't have the fan switch or the relay. How do you run a dealership and service area and not have parts?

Aaron Buckley · **Posted:** Tue May 05, 2015 12:31 pm

Did you call and order one before stopping by? For obscure parts that aren't common failure points, I'm not surprised they don't have them in stock. - AB

Chris Halweg · **Posted:** Tue May 05, 2015 1:13 pm

Aaron Buckley wrote:

Did you call and order one before stopping by? For obscure parts that aren't common failure points, I'm not surprised they don't have them in stock. - AB

Yes, a good way to know if it is a common failure point is if it is in stock.

RodneyWright · **Posted:** Tue May 05, 2015 2:07 pm

ugg, running out of options. new relay gives the same result. no low speed, only high speed fan. Running short on things to replace. So no AC only runs the fan on high. With AC, low speed fan kicks on w/ no issues. What the heck am I missing? Something burned, but can't find any bad wires.

RickyBeam · **Posted:** Tue May 05, 2015 4:19 pm

Is the fan computer controlled? Can you check what the ECU thinks the engine/coolant temp is?

(I futz with VWs, and the answer is yes to both. In the Guthrie FLOG, there's a switch where the battery should be to force the fans on -- I think at one point both sensors were bad; there ARE a lot of DTCs on that car. There's a lot of stupid in a VW for "german engineering".)

Vincent Keene · **Posted:** Tue May 05, 2015 4:32 pm

RickyBeam wrote:

There's a lot of stupid in a VW for "german engineering".)

QFT.

RodneyWright · **Posted:** Tue May 05, 2015 4:56 pm

RickyBeam wrote:

Is the fan computer controlled? Can you check what the ECU thinks the engine/coolant temp is?

I'm assuming it is. I have an old SCT handheld, but it seems I can't get to the fan info w/ out uploading a tune. I've tried these when I first bought the car and wasn't a fan of the changes. Don't want to upload and change settings only to back load the original tune.

Doesn't address the issue of why the low speed fan stopped working in the first place.

I did another test buy running the AC for about 15 minutes. Car never went over 180 on the gauge while it was running. Turned off the AC and the fan kept running for another few minutes and then turned off. I don't know if that was a timed delay or if it received a signal to turn off. Car continued to run and started back up to 220 before the fan kicked in again. I could buy a fan, but I don't know if that's my issue. I've looked into some of the wire looms and not seeing anything weird so far. I hate chasing electrical gremlins like this....

RickyBeam · **Posted:** Tue May 05, 2015 5:07 pm

RodneyWright wrote:

Doesn't address the issue of why the low speed fan stopped working in the first place.

Bad sensor reading at the ECU would explain it.

For the record, my Tempo used to do the same thing. If it wasn't moving, it would over heat. Never bothered to look at it. Turning the A/C on would engage the fan. Leaving the cabin fan at "off" would leave the compressor off. Problem solved, for a broke college kid.

RodneyWright · **Posted:** Tue May 05, 2015 5:18 pm

RickyBeam wrote:

Bad sensor reading at the ECU would explain it.

For the record, my Tempo used to do the same thing. If it wasn't moving, it would over heat. Never bothered to look at it. Turning the A/C on would engage the fan. Leaving the cabin fan at "off" would leave the compressor off. Problem solved, for a broke college kid.

Which sensor? I replaced the fan sensor. From what I understand that's the only "coolant" sensor on the car. It's reading the temps in the head and is supposed to act appropriately to feeding info to the fan. That's why I changed that out as my first plan of attack.

As I had mentioned, I had smelled something. It may have been outside and it may have been something under the hood. It wasn't present in the cabin of the car when I was moving, only sitting still w/ the windows down.

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