Ronnoc74

'93 Civic Hatch CX

I've searched but I haven't found anything that is specific to what is happening with my car.


My Hvac system recently started working whenever it wants to. No matter what position I have the fan switch in (other than the OFF position), it will come on and off as it pleases. Usually when I'm starting from a stop and my revvs drop from letting the clutch out, it will turn on for a short time, then shut off. Other times ill just be driving and it will randomly turn on.

I replaced the resistor on the blower motor housing today because I remember reading somewhere that that could be the cause but it didn't fix it. The one I took out of my car looked to be in alright condition, I didn't notice any of the metal wire looking things to be broken, just the white stuff that is on there was missing in a few places.

I just installed AC in my car today and once I get the system charged it will be ready to go but it won't be worth anything unless I get this problem fixed. I'm not sure if its related or not but even before I installed the AC on my car, whenever I pushed the AC button, sometimes the little green light would light up and other times it wouldn't.
Another thing I had a question about is the thermostat wiring on the evaporator. The donor car I got the AC stuff from was a '95. The plug that is part of my wiring harness is a two pin plug, and the socket it goes into on the thermostat is a 3 pin. I'm going to get the 3 pin plug pigtail from the junkyard, but I would I wire this into my wiring harness?

Any help is appreciated.
Thanks in advance.

Ronnoc74

Can anyone help me out? Is there a way to test something to see why it's not working?

Ronnoc74

Going to the junkyard later today. Should I try and find the pigtail for the 3-pin connector for the thermostat or try and find the two wire thermostat so I don't have to re pin the connector?

Ronnoc74

I could really use some help with this...

Bought the 3 Pin pigtail yesterday at the junkyard. How do I wire it up?
The 2 Pin plug that is in the car now has YEL/WHT and BLU/RED wires. The 3 Pin plug I got yesterday has YEL/WHT, BLU/RED, and BLK/YEL wires. What is the BLK/YEL wire for? Am I better off trying to find a 2 Pin thermostat? I looked briefly for one yesterday but I didn't see any.

Ronnoc74

Can someone please help me with this? I'd like to have A/C for IA this summer but I can't unless I get the blower problem fixed

Ronnoc74

Getting close to 200 views and no one can help me out.

Am I not giving enough info about the problem or something?
I'm getting desperate. I need to figure this out soon....

instructor74

Get a new fan switch it is not common but they do go bad. They are not easy to change and take some time to replace. I had to replace mine a year or to ago for a simlilar problem. DONT bother geting one from a junk yard they are just to much of a pain in the butt to get to and a new one is not very expensive. You will need to pull the radio out to give yourself some room to work good luck

Former User

If you ground the Blu/Blk wire at the rear of the heater control panel, does the fan now run on high continuously?

Ronnoc74

I just spent the last hour or more trying to get the climate controls out. I finally did. I grounded the BLU/BLK wire like you said and nothing happened. I tried another climate control I had sitting around from when I got the car (I replaced it because the temp. **** was broken) and still nothing.
What would that test have proved/disproved?

Ronnoc74

also I forgot to mention that whenever I would feel the relay in the underhood fusebox for the heater blower motor it would be hot to the touch. I'm not sure if that has anything to do with this or not though or if that's normal

Former User

Did you turn the key to ON(II) after you grounded the Blu/Blk wire?

The test will tell you whether the problem is located upstream of the switch in the circuit versus in the switch/heater control panel.

Former User

If the test above says the problem is located upstream of the switch, then you may want to test the relay, among other parts including the motor. Relays normally do heat up.

Ronnoc74

Yeah, I turned the key to the second position and nothing happened.

What do I do next?

Former User

Run power and ground wires directly from the battery to the blower motor. Does the blower now run continuously?

Ronnoc74

I took the blower out and ran direct power to it and it turned on. I did notice though that the plug that goes to it, the ground looked weird. The plug was like brown on the ground side like its been burned up a little inside previously.

Former User

When provided with constant power and ground, does the blower motor run continuously at high speed? If so, it is fine.

In the blower motor plug, the ground wire is Blu/Blk and the power wire is Blu/Wht. Which one is discolored?

Blower motor connector:
What voltage to body ground do you measure at the Blu/Wht wire with the key in ON(II). With the key off and the blower switch set to MAX, what resistance do you measure at the Blu/Blk wire?

Ronnoc74

Yeah it runs at full power.

The BLU/BLK wire is the one that is discolored.

With the blower setting on 4 and the key on II, I measured .02 then it dropped to 0.00 and never went back up.

Which setting do I put the multimeter to to measure resistance?
http://i639.photobucket.com/albums/uu115/RonJ_HT/MM.jpg
That's the Multimeter I have, sorry for using your photo, lol.



EDIT: If I put the MM on the --->+ symbol I would get a reading anywhere from 13-18 and if I put it on the 20 Ohms setting I would get the same numbers but the number after the decimal kept jumping around.
I'm not sure if this is the correct way to test for resistance or not though.

Former User

More information is needed. Is this a DC voltage measurement at the Blu/Wht wire? What did you use as ground?

Resistance is measured with the multimeter dial turned to Ohms (horseshoe symbol). Use the 200 scale.

Again, more details are needed. What wire were you testing here? How did you do the test?

Ronnoc74

Yay for working a twelve hour shift...

I'll go out and re-check the measurements I took because from reading your response I'm pretty sure I did the tests wrong.

EDIT:
Blower setting on 4 with key on II, I got 10.67 DCV from the BLU/WHT wire. I used the same ground that I used for my lights-on chime.

When I measured the resistance on the BLU/BLK wire, I had the key off and the blower on 4 and put the multimeter on the 200 Ohms scale. I put one probe of the multimeter to the BLU/BLK wire and the other to the body ground I used for the previous test and I got a reading of 19. I did notice though that if I barely touched the blower setting **** the numbers would jump around and peak somewhere in the 100's then slowly trickle back down.

Ronnoc74

Need more details?

Former User

Let's return to the Blu/Blk wire in the 6P fan switch connector (wire harness side). If you unplug the 6P connector from the fan switch (see below) and then ground the Blu/Blk wire terminal to the metal frame under the dash, the fan should run continuously when the key is turned to ON(II). Does this happen?

Ronnoc74

Sorry for taking so long to reply, I've been prepping my car getting it ready for some fresh paint for IA.

Did the test and I got nothing at all. What could that be a sign of?

Former User

The Blu/Blk wire is most likely broken. Test the Blu/Blk wire for continuity between the blower motor plug and the fan switch plug.

Ronnoc74

I'm about to go out and test it now, but just out of curiosity, how do you know its the Blu/Blk wire? Could it be one of the other wires too?

Former User