Rep Power: 0

I have checked all fuses and all the relays are working...I replaced the blower motor resistor...blower motor relay...can jump the blower motor and it will come on....can jump both fans and they come on.....put the ignition in the on position turn on the fan and both fans under hood car come on and go right back off....a/c compressor does not engage.....help me out...what am I missing?

 
Rep Power: 517

The AC and everything related to AC is disabled because the HVAC control panel 'sees' the blower fan is not running. Fix that fan problem first.

Where's your voltmeter?
What is missing from the fan motor, why does it not run? (power OR ground has to be missing, which one is it?)

 
Rep Power: 0

I have power to blower motor...I replaced blower motor relay....I don't how to check for ground on meter....I also replace blower motor resistor....I can take the number 2 and 4 pin and jump them and the blower motor will come on

 
Rep Power: 517

Connect meter lead to a known good battery positive.
Other lead connects to suspect wire.
If meter shows 12v that wire must be a ground.

Hold off for a bit though.....

It's not really a resistor. It's a power transistor. That's how they get variable speed from the motor instead of 4 speeds.

Discount parts used? Did it work at all after replacing it?
Try another?

Do you still have the original part?


Is that jumping the two fat wires on the transistor plug?

 
Rep Power: 0

Yes....on the transistor plug and blower will come on

 
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I have tried both and still the same result the new transistor and the old one

 
Rep Power: 517

Ok so there's ground that can run the fan motor.

Either the power transistor is bad, or the control panel can't turn the transistor on.

Is the new transistor a cheapie or did you get it from Honda?


Want to take apart the old transistor to see if it is bad (failed in the most typical manner)?
Split the unit open












Behind these pins is a thermal cutoff fuse, or TCO.
So you get to this point and measure ohms as shown, see if this fuse is open (blown)

If it is, you could bridge the TCO with a temporary jumper wire---preferably with a fuse in it-- to see if it will again run the blower fan. (I have a few test units that have been hacked this way to speed up diagnosis)
You cannot do this more than a few seconds because the unit can overheat pretty quick if it is not in the blower housing.

 
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What kind of ohms should I get if it is bad? And yes I got a blower transistor from advance auto

 
Rep Power: 517

Bad would be open circuit.

 
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I will try tomorrow....I am get some sleep....been a long day

 
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I get O.L. on ohms....so that tells me that the circuit is closed....means the
original transistor was good....

 
Rep Power: 517

OL on most meters means 'over limit', or open circuit. Same as when your meter leads are not touching anything, that's open. Bad fuse, no continuity inside it.

Zero (0) ohms would be the reading of a good fuse.
Zero, same as when your meter leads are touching each other.

I'd jumper across that open fuse and plug it into the car real quick to see if the blower will stay running long enough to make the AC run again. That could at least tell you if your new transistor is bad without breaking it open to test.
Use a heavy wire and set fan control on a low speed though

A bad fan motor drawing too many amps could blow the fuse, and running hot because of clogged cabin filters can blow it too.

 
Rep Power: 0

[QUOTE=ezone;4713546]OL on most meters means 'over limit', or open circuit. Same as when your meter leads are not touching anything, that's open. Bad fuse, no continuity inside it.

Zero (0) ohms would be the reading of a good fuse.
Zero, same as when your meter leads are touching each other.

I'd jumper across that open fuse and plug it into the car real quick to see if the blower will stay running long enough to make the AC run again. That could at least tell you if your new transistor is bad without breaking it open to test.
Use a heavy wire and set fan control on a low speed though

A bad fan motor drawing too many amps could blow the fuse, and running hot because of clogged cabin filters can blow it too.[/QUOTIdian

So I plug in the old transistor....use a jumper wire to battery for a few seconds and turn on the fan real quick on low to see if I can get a/c and blower motor to come on...is this correct....have any photos to show how to do this?

 
Rep Power: 307

Did you have the new transistor mounted in place when tested ???....If not the TCO will not last very long ??

Still have your original transistor ?? Is TCO open on it ??

 
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I have the original....I haven't done the test yet

 
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I had to go get jumper wires

 
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The old transistor is open and haven't tested the new one yet

 
Rep Power: 307

A good test for open TCO is to have the fan set to ON, and then watch the white fan blades very closely with cabin filter out when you FIRST turn the key to II. If it spins/moves a tiny bit the TCO is open.

You must mount the transistors correctly in place to cool them properly.

 
Rep Power: 0

The old transistor and the new transistor are open after test was just run.... So does that mean the new transistor I just purchased is not good?

 
Rep Power: 517

NO! Jumper is to take the place of the bad TCO fuse.

Sounds like it's bad.