Where is 300E Heater Blower Motor Fuse? Please help running out of cars.
 

My daughters new Honda, yes Honda is two months old and went into limp mode and set check engine light. I put her in my wifes car, my wife in my 300E and drove my backup which is the C.

I now have to drive the Honda 70 miles tomorrow in limp mode not being able to go over 50MPH to the dealer and the blower quit working on the 300E. It's over 100 degrees so it's too much to expect her to drive it without an a/c although I will have to drive the Honda with the a/c broken along with the other problems.

In the fuse box lid on the 300E it simply says "Heater Blower Fuse Outside Fuse Box."

Can someone tell me exactly where to look. With my luck it's probably tie wrapped to the most unreachable part of the evaporator.

Please help ASAP.

Thanks a bunch,

Larry
It's kind of over by the left front upper strut mount, under the hood near the main fuse box. It looks like a smalll black plastic box with a flip open lid. You can pull the cover open and there is a strip fuse under there, similar to a fuse on a glow plug relay.

Gilly

Gilly,

Thanks a million, I found it and it's good. I even checked it with a voltmeter on both sides of the fuse. It has battery voltage with ignition switch on, then drops to 11.4 volts with fan switch and climate control on.

Is there a relay associated with it?

My book only covers manual heater/blower controls.

Thanks again for the help,

Well without climate control wiring info in my manual I'm flying blind, but one of the relays in the box behind the fuses was VERY hot, much hotter than the others.

If indeed the relay that was hot was the correct relay, maybe the motor is jammed or something.

My wife will drive my old pickup tomorrow. It uses gas like the tank is leaking, but it runs good and has an a/c that will make ice cubes in the cab.

I will be gone this weekend, so maybe I can get enough info to get back with it next week.

Thanks a bunch for the response and any prior experiences troubleshooting this system will be most helpful and appreciated to hear.

Have a great day,

I don't believe there is a relay Larry, just the fan controller (regulator) under the blower itself. I'd bet on the fan brushes being kaput.

Gilly

Larry -

I just went through this on my 124 last weekend. Fan was working fine, stopped for dinner, no fan. I've got it working again, but haven't really identified a cause. It was one of those take out, test it, it works, reassemble it, it works kind of scenarios.

The most likely problem is worn comutator brushes on the motor. You can probably extract some more life from the fan by taking it out and cleaning up the brushes. Quite likely one of them cocked at an angle and lost contact. Alternatively, the brushes can be replaced for a modest sum - plenty of threads on that topic here.

Pulling the fan motor isn't too bad a job. Perhaps 2 hours the first time, much, much less once you've done it.

Best of luck,

- Jim

My manual says to pull the windshield wiper motor and remove the fan from the cowl. That is for a heater only car (European manual.) Is this true on my US car, or do I remove the passenger kick panel?

Thanks for your help. I fully expect it is brushes or jammed by something.

Have a great day,

Everyone will be proud of me. I did a search and found JSlobotsky's picture sequence.

I am now contemplating whether I should just go straight to the blower motor or check the controls first to see that voltage is getting through. The blower quit all of a sudden.

Thanks for all the replies. I am tied up this weekend, but I guess next week and weekend I will get some wrench time on this.

Have a great day,

I checked the PBU first - it's only about 15 minutes work. I pulled the wood covering the PBU - two small, vertical screws just above the radio. A stubby phillips screwdriver is required.

Flip open the top of the left hand wiring plug. If memory serves, the blower control signal is pin 12 (third from the back in the left hand row - I can look this up to be sure if you need it). Monitor it with a DVM - should see voltage slowly increase from 0-5 volts when switching the climate system from off to EC. If you do, the PBU is sending a signal to run the fan.

Apparently there's also a plug in the engine compartment, somewhere near the brake booster, which gives access to the blower control signal. I was too lazy to look for it when I knew I could get easy access at the PBU.

The blower control unit is located directly below the fan, so even if it's the problem you have to pull the fan. I bet if you open it up, and give the fan a spin and/or rap with a hammer it'll start right up.

I understand George Murphy sells the correct replacement brushes for ~$20. I'm going to order a set of these for next time the fan stops. Guess I'm too lazy to work over a set of non-standard brushes to fit.

- JimY

Are you sure it's simply not the #5 fuse in the main fuse box?

Thanks for the replies.

I checked all fuses including the bar fuse in the holder forward of the main fuse box.

I will have time to move it in the shop and start tearing it apart next week. I have some heavy stuff pressing for this weekend.

Have a great day,

Some other posts have indicated that an iffy ignition switch can prevent he fan from working. Looks like these were mostly intermittent failures, though.

Still not sure why they would have this much amperage going through it, but may be worth looking into. Certainly the easier fix.

Perhaps your 11.4v rules this out, though, since I would think that would be enough to spin it.

Yes, according to my manual climate control wiring diagram, the bar fuse is AFTER the ignition switch. I have had the ignition switch malady to deal with before, but it was on 123 cars. I don't think it is very common on the 124.

Thanks for the replies,

Just wanted to report back on the problems covered in this thread.

First the Honda status. I took my daughters brand new Honda to the dealer in limp mode August 1 and still don't have it back. It was in limp mode and wouldn't run over 50MPH. In another thread someone told about how Hondas and Toyotas never break, only MB's break. I think that this person was not facing reality. I think her car might be headed for a lemon law replacement.

I got a blower motor, tore things apart to get to it, and sure enough, the blower motor was frozen, I suppose the bearings were shot. I thought it was something like that since the voltage at the fuse decreased when turning on the blower motor.

Thanks to JSlabotsky's post with pictures, I got in and replaced it pretty readily. Had I been flying blind it would've taken longer to figure out how it comes apart. It was a real trick using my puller on the fans.

Have a great day,