Headlights dim, A/C runs with key off, lites on.

[leadman]

On the way home from Michigan to Arizona Thursday I left the lights on at a fuel stop and my wife noticed the a/c blower was still running. I turned the lights off and the blower stopped. We continued to drive towards Phoenix with no problems noted as it was still daylight.
We drove into Phoenix just as it was getting dark and I noticed my headlights were very dim on low. A little brighter on high beam but still not good. We had the a/c blower on for about 13 hours that day.
Today I was looking over the wiring under the flip up dash and found a 25 amp fuse and rubber holder melted. This is the bottom fuse box on the left and the left fuse holder attached to the outside of the fuse box, probably by Winnebago.
I checked the wire code and it is supposed to be for the a/c blower but I went no farther with inspection today.

I'll get back to it in the morning but was wondering if the F53, 1999 version has a light control module?

Not able to find much info on the internet on this.
Also someone wired in too small relays to the high beam headlights at one time. One of the items I have been meaning to take care of but other repairs have kept me busy and until now no issues with this were noted.

[Mekanic]

Originally Posted by leadman

On the way home from Michigan to Arizona Thursday I left the lights on at a fuel stop and my wife noticed the a/c blower was still running. I turned the lights off and the blower stopped. We continued to drive towards Phoenix with no problems noted as it was still daylight.
We drove into Phoenix just as it was getting dark and I noticed my headlights were very dim on low. A little brighter on high beam but still not good. We had the a/c blower on for about 13 hours that day.
Today I was looking over the wiring under the flip up dash and found a 25 amp fuse and rubber holder melted. .....

Not able to find much info on the internet on this.
Also someone wired in too small relays to the high beam headlights at one time. One of the items I have been meaning to take care of but other repairs have kept me busy and until now no issues with this were noted.

OK I see
4 issues and it is possible that there are 3 (or 1)cause(s)
First Id Bypass/unhook anything it did NOT Leave Ford with.

Fix the Fuse holder and see if that solves any other problems.....

Then get a volt meter and see Why the headlight s were dim
(remember 13 volts is no good if the grounding is IFFY)

And so on and so forth....

[leadman]

I found the problems yesterday and will do the needed repairs today.
Someone had powered the extra headlight relay from the hot wire going to the a/c relay. It was tucked behind some other wiring. This is why the a/c ran with the headlights on as it was back feeding. It has been removed along with the extra wiring. The a/c now seems to operate normally with a new fuse holder soldered in place.
The voltage was low going to the headlights, around 11 volts. Found the Ford plug had gotten moisture in it and corroded the terminals. One terminal is so bad it was not improved by cleaning. Guess 20 years and the last 3 months in Michigan where it seemed to rain much more than I remember from when we lived there took its' toll on this plug.
I removed the harness and used my boat battery to test the wiring and except for the park/turn signal and headlight plugs the harness is good. No corrosion in the wires. The park/turn signal plugs are GM and the headlight plugs generic so I bought replacements so will solder them on today and cover with shrink sleeving. The Ford plug will be removed and wires soldered and sleeved also.
I have ordered 4 new glass headlight housings that come with led bulbs to hopefully give me good lighting in case I have to drive at night again. This won't be in until Thursday but they are sold as a direct replacement for my 4" X 6" four bulb headlight system.

[youracman]

Leadman- Just some info to pass on to you and others, FWIW: Over on the Foretravel Forum, one of the guys advised that, on a motorhome, one should always use "Marine Grade" heat shrink tubing. I'd never heard of it, but found it here:https://www.amazon.com/Ancor-Marine-.../dp/B000QCPKE8 I believe it is supposed to be waterproof; some of the bargain basement stuff..... not so much.

Safe travels............

[leadman]

Never heard of marine grade either. Most of what I used is military spec from a business a person I know used to work at. They made components for military contracts.
I also used a few butt connectors that have heat shrink tubing built right on them. They are also from a different business for emergency vehicle applications. I heated one then tried to pry it loose from the wire. Even after cutting the wire I had to use a knife to cut it off the wire. I think it should last quite a while.
Repairs seem to be complete other then changing out the headlights as they are not due to arrive until Thursday. I now have 13.6 volts to the headlights with the engine idling. The next trip should tell for sure it is fixed.

[leadman]

The headlight conversion "kits" were junk so sent them back and got a refund.

I bought 2 old school rectangular 55w halogen driving lights and will install these on a separate switch. Seldom drive at night so these should be ok.

[Unplanned Tourist]

Did you get the 13.5 volts with the headlights hooked up?
Lots of rigs use under sized, or too long wire runs for the headlights. That's likely why the previous owner installed the relays.
Voltage often is much lower when the lights are in use.
Happy Glamping.

[leadman]

The 13.5 volts was with all the lights on, engine off, high beams on. The wiring is 14 gauge so should be fine.