1991 Honda accord Heater/ac switch problem
 

I guys it Pito once again....Thanks to Poorman212 and Crispin i solved the previous problem of no dash lights and tail lights... look at my old post for knowledge.

i have a switch that does not work. it doesnt function in all positions....i used the test light i dont have any constant power..on or off from the switch itself...

I figured that the large blue wire w/ red stripe is the power source and the large black wire is the neg..all the other smaller wire is to control the speed of the motor.

i do have light power to the buttons that position the vent to direct the air flow... i do hear that working. no motor blowing.

Since i had the dash already dismantled from the previous problem...i ran the wires down the left side of the dash board then it made u turn and came back down the the center and underneath the carpet...then made a right turn and underneath the two computer consoles...the large black wire gets grounded at the passenger side kick panel with two other black wires. the large blue with red stripe wire continues up that same side....thats where i am at right now.

the blower fuse is not blown.

Did I post this right?

Yes you posted it right.

I am going to wait for Poorman or someone else who understands how the A/C controls are wired to chime in.

I do know that there are 1 or 2 relays involved with the blower system.

My guess is going to be something to do with a relay.

Question, did the controls used to work? If so what happened?

Pito, also have you downloaded the Service manual yet?

Looking at the wiring diagram (page 948 in service manual) there are 2 relays involved that must be working.

1 is in the underhood fuse box and the 2nd is under the dash somewhere.

You should not have any power at the switch, like much of what honda does things are controlled by grounding circuits

How it works is going to the motor is a yellow/black wire - that is the power source.

The blue/red is the other wire that goes to the blower motor (from the blower resistor) and it carries the ground.

Here is what you should do.

Probe the yellow/black wire on the blower motor with the key in the 'on' position and see if you have power there. I guess you do not. At that point I would pull the under hood relay and tap it some and re-install. If it still does not work I would replace the relay.

I downloaded the service manual...I will read up on that tonight and tomorrow.

Did you try this test yet?

Probe the yellow/black wire on the blower motor with the key in the 'on' position and see if you have power there. I guess you do not.

At that point I would pull the under hood relay and tap it some and re-install.

If it still does not work I would replace the relay.

Yes wire diagrams are fun reading :)

As crispin said, check for power at the motor.

If there is not power there, I personally would start with the underdash relay. Test the relay, test the inputs to the relay.

Sorry guys..I had to work a lot this week...wife went to work as well...she can drive now at night...I still have the entire dash disassembled. My wife nags me when are you to finish the car...this is where I'm at.....besides the aforementioned ..I changed the blower relay....its not the relay...I returned it and got my money back...I had the old relay tested...its still good.

Pito - we said to test for power at the blower motor before you start replacing parts.

Have you tested for power at the blower motor yet?

No power at the motor....I jumpy the motor with power and ground..the motor does work.....inputting to the relay from battery is not there.....I turn on the ignition and I have poet to the number one probe of the relay socket...but after that nothing...there is no constant.

Which relay Pito, there are 3 different ones?

Accord to the diagram of the 91 accord....its the one of three just above the under dash. Fuse panel...the one in the middle...I took it out and it said RIght behind ...blower motor..so it can't be confused with anything else. What other relays are there to check?

Check your fuses. It looks like there is a fuse in the engine bay and the fuse box under the dash that you should check.

If you unplug the relay, check for voltage then ground with the key in the II position on the pins of the fuse box. Two of the pins should have 12V to ground. With fan speed set to O (off), only one of the pins will have continuity to ground that did not have voltage. The last pin should have continuity to ground when you turn the fan switch to something other than off.

ok i will check the pins tomorrow...

My wife hates me right now..I still haven't done anything to resolve the problem of the heater switch. The entire dash is disassembled apart from the cluster and the hazzard switch.

Sounds like we (you) need to have a little fun tomorrow and see if we can figure this out :)

Be nice to give her car back with everything working for Mothers Day, she would be happy.

Mine is going to be "heck" all over again no matter what I do.

ok guys i got the car back...im back to working on the car again.

I was wondering where you been Pito.

Good to hear from you again.

http://i1069.photobucket.com/albums/...5-18155245.jpg
That is the photo where the heater motor is located just above the drivers fuse kick panel.

I recurs the fuses...I ran I wire from the underhood fuse box and contected it to the yellow/ BK stripe with from the motor and leaving the blue/red stripe untouched.....the motor did turn on. The relay was not in its socket. So I know so far the motor OK.

Now as far the pic I mentioned...( using a regular mechanics test light) I tested all four sectors...no power. With the key ignition turned on ...only the upper right sector has power with the fan switch turned off. Now with the fan switched turned on ...nothing changed..no other sectors has poet but that upper right one I mentioned.

I will PM poorman and see if he can help, he is better at the wiring diagrams then I am.

Sorry, at work I can't really get on here...I have to go somewhere and use a free wi-fi.

Anyway, we are missing power to one of the pins. From your description - No power to any pin with the key off - The underhood fuse (#18 - 30amp) is the first thing I'd double check....should be the white wire to the relay.

Getting power to one pin with the key on means the underdash fuse and switch are good

I rechecked the fuses. All OK. I did a test run with a wire from the battery to the relay. I placed it in the fourth sector of the pins....lower right. Becoming a constant. I turned the ignition on and the blower worked. Why would the wire go bad?

I still have to do it...I had no time. I had to pick up the wife at work. I will give a shot tomorrow. I bought a relay just invade if it was that but it wasn't...its the wire...weird.

Pito

Perhaps you had a mouse living in the car some.

Those things love to chew wires which can cause all kinds of strange wiring problems, like those you are having.

Best I can tell, you are missing the "constant" power that comes from the under hood fuse panel....are there "other" electrical issues with the car?

Anyway, at least you have the blower working again :)

OK this what I did....first I did a test run. I ran a wire from the battery and directly to the blower relay and making contact to the lower right whole...which made me have power to the switch itself. ...day came and I ran a smaller wire and attached it to the lower right peg of the relay itself. The other end to a fused tap in for the fuse box...I used a 20amp fuse after trial error going from 5-20 amp fuses...I got the blower up and running..I put the car back together...

I have new electrical problem with the window motors. They work intermittently. It works when it wants to. Should we go from here or start a new thread post?

I say keep it here.

Also was that fuse tap the one you ordered from China???

If so it came in handy after all :)

No I did not use the china fuse. I bought a fuse at auto parts store for $6. Poorman how do we tackle the window problem?

First, hard to fix things when they work.....meaning you can only test when they are not working.

When they act up, is it all of the windows or "a window"? If it is one, which one.

With the other electrical issues, the pin that is missing power to the blower relay comes from the under hood fuse panel.....which is the same panel that should have the fuses for the windows.....hummm.

Anyway, key on- four wires should be hot. WHT/YEL, BLU/BLK, GRN/BLK and YEL/BLK. Of course the BLK (two I think) should have good ground.

First of all it not the fuses...and yes its all windows

Agree on the fuses, I'm just wondering if something is up with the underhood fuse panel. There are connections under and inside of it that might be bad.

You can also check the BLK wires to be sure they have good ground - or add another ground.

OK this is what I got .... the relay for the power windows is is located in the u/h fuse box and it clicks when I move it. I tested the front pass door while wide open...click no power...I press down on the relay hard and click and the flipping the switch I have power. I let go...no power. That what I have to do yesterday...it was hot in NY. My wife went to work...I will have to stop her off to play with the car tomorrow. What do you think may be the problem. I had a new relay and tried it..same result. So its not the relay...

Ok ....im back guys...now i got no heat in my 1991 accord dx...wtf..blower is working fine...no heat blowing out of the vents

How have you been? I guess good since we haven't seen you in a while :)

Anyway, a few things to check......

1) Have someone turn the heat knob from hot to cold as you watch the cable on the heater control valve.....is the cable moving?
1a, if not-pull the knob and be sure the shaft is not broken. If not broken check the cable movement from the pass side floor board......look up the blend door adjustment in the manual.
1b, is the cable on the heater control valve is moving. Check the temp on the hoses before and after the heater control valve (they can and do fail inside). If the temp on the engine side is hot and not on the heater core side then suspect a bad valve.
1c, if the temp on the hoses into and out of the heater control valve are the same. Compare those to the outlet hose from the valve.

Ok will check the cable tomorrow

Forgot one piece of info last night. The heater control valve is connected to the knob inside the car by two cables.

One from the knob to the blend door lever - found by looking under the glove box. The other goes from the blend door lever to the actual valve under the hood. If you have downloaded the shop manual you can find the procedure for the "blend door adjustment" and will see this set up....again just adding what I forgot last night :) - Getting old sucks