2004 CRV :: AC Stopped working :: Replace Transistor / Thermal cutoff?
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Thread: 2004 CRV :: AC Stopped working :: Replace Transistor / Thermal cutoff?

  1. #1
    crv|oc Rank: Member
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    2004 CRV :: AC Stopped working :: Replace Transistor / Thermal cutoff?

    Today the AC on my '04 CR-V stopped working. I left work and it ran for maybe 3 minutes, then just stopped. I was hot today, about 100F. The car has maybe 55,000 miles on it.

    The AC light goes on, but the blower doesn't run, not even if you turn it up all the way. I went to try it again this evening. It still doesn't work, but when I turn the key on and turn on the AC the radiator fan goes on for a couple of seconds, but only once for every time I turn on the key. Also, when I have the engine on, and I turn on the AC I can hear the compressor go on.

    I've read a post on this forum here, explaining how to check the relay and maybe replace the resistor.

    I had the same problem with our Odyssey van maybe 2 years ago, and browsing around I came on a site I can't find now as well as a Youtube video (here), explaining how to replace the transistor module.

    I took the module out as it explains how to in the video, and (according to the other site) I just replaced the Thermal Cutoff, which looks like a small diode. It is available at Digikey (here) for about 50 cents each.

    The Odyssey unit is a finned metal thingy with a transistor and the thermal cutoff in it. For anyone that had done this, is the CR-V unit similar? Does it maybe use the same transistor and / or thermal cutoff?

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  3. #2
    crv|oc Rank: Member
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    You are on the right track. If the blower transistor fails, (does not work on any speed) than the A/C control unit will not turn on the compressor. The resistor has a feedback circuit that sends voltage back to the control panel to tell it that the blower is working. It is located above the passenger foot area and held in by 2 screws.

  4. #3
    crv|oc Rank: Member 4string's Avatar
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    Does the blower have it's own fuse?
    '05 CR-V 2WD LX (bone stock) - My new DD!

    '97 Toyota 4runner 4x4 - Lifted, locked, armored, and geared - My trail rig!

  5. #4
    crv|oc Rank: Member
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    How to fix AC Transistor Module

    This is primarily explaining the fix for the AC Transistor Module for a 2004 CR-V. It includes info on how to properly and reliably check the components in the module and where to get replacement parts. The module fits several Honda models, including
    Civic 2001-2005 all models (Hybrid) . . . CRV 2002-2006 all models
    Element 2003-2009 all models . . . . . . .Accord 2003-2007 all models
    As I explain below, the module for my '01 Odyssey was very similar and I assume other Hondas use it also.

    Last year, almost to the day, the same thing happened in our '01 Odyssey van. My wife complained that the AC wasn't working. When I checked it out, the blower motor (that runs the interior fan for the AC & heater) wasn't working. All the fuses were ok, and it didn't seem right that it would just stop like that.

    Browsing around on line, I learned about the famous Transistor Module, and was able to figure it out. The transistor was ok, but the other component in there, a 'thermal cutout' was bad. This was last year, on one of the hottest days of the year.

    The same thing happened this week to my CR-V. When I start the car and then turn on the AC, the AC light goes on and the compressor runs, but only for a few seconds. The light stays on. The compressor will not start again unless you turn off the car first. With the blower not working, there is no air circulation in the car (seemingly) at all.

    Looking around on this forum, there are many posts explaining how to remove the module, but none telling how to fix it.

    Getting the bugger out was a PITA. I first looked 'behind' the glove box, like how you get to the cabin filter. Then I read some more and found it's under the glove box. I located it, but couldn't get the screws out. Here I am, laying across the front seats, with my right hip on the driver seat, and my shoulder and head down near the floor trying to look up under the dash. It's 100 F outside and more in the car. The sun is in my face, and I'm there with a flashlight and a mirror trying to see under the dash, where almost everything is black. And then I get a bit of acid reflux...

    I try again later on, in the evening, but don't have a screwdriver short enough. You need a really short #2 philips driver. I finally managed to loosen it and get it out.

    I popped the top off it, and here is a photo of it...------- and another...
    . . . .
    -----
    The unit has four tabs that poke through the case to connect to the wiring harness. It is just a circuit board on a heat sink with a transistor and a 'thermal cutout' mounted to the heat sink, under the board. The circuit board has three leads for a transistor and two (at the other end) for a 'thermal cutofff' (that I'll call 'TCO') that were obviously soldered to the board after it was assembled in place.

    I unsoldered the five connections, and pushing the two plastic 'hooks' aside, lifted the board off. Remove the screw and the small black clip holding the TCO in place and it looks like this:



    The clip is resting on the upper left corner of the unit.
    The part marked K2313 is a metal–oxide–semiconductor field-effect transistor (MOSFET). This is a device used for amplifying or switching electronic signals. In MOSFETs, a voltage on the oxide-insulated gate electrode can induce a conducting channel between the two other contacts called source and drain. It is a Toshiba 2SK2313, you'll just see the K2313 part on the transistor case. DigiKey has the exact part, here, Mouser has it here and Toshiba's data sheet is here. The 2SK2313 crosses to NTE2920, which is slightly different but can be made to fit, and is available here.

    It is interesting to see that the transistor data sheet notes: Using continuously under heavy loads (e.g. the application of high temperature/current/voltage and the significant change in temperature, etc.) may cause this product to decrease in the reliability significantly even if the operating conditions (i.e. operating temperature/current/voltage, etc.) are within the absolute maximum ratings. Please design the appropriate reliability upon reviewing the Toshiba Semiconductor Reliability Handbook (“Handling Precautions”/Derating Concept and Methods) and individual reliability data (i.e. reliability test report and estimated failure rate, etc).

    To test it: Check the forward and reverse resistance with your ohmmeter set to the highest "R" scale. The leads are labeled on the board, G, S,& D. It has very - extremely - high input resistance, so you should get almost infinite resistance both forward and reverse across the gate and drain or source. Between the drain & source it'll look almost like a short. On my unit the transistor was good.

    BTW: Forward resistance would be with the red meter lead on the Gate and black on the Source or Drain, and reverse resistance is the other way around.

    On my unit the transistor was good. To check the TCO, set your ohmmeter to the highest "R" value check to see it it has continuity both directions; it will probably be open. The part is available for 45 cents from digikey.com, here. The data sheet for it is here.

    This is what I received from Digikey, one of the four I bought when the AC went out on the Odyssey a year ago:



    This is a pic of the one I just removed from the CRV and one of the ones I bought a year ago,
    the new one is on the bottom:


    I put the new one in place with some more silicone heat sink compound,
    that you can get at any electronics or computer parts store.
    Here the clip and screw are in place:


    Here the board is back in place,


    and resoldered the five connections,


    I didn't bother taking a pic of the unit with the cover on, I just went and wired it back in place, and IT WORKED! Then I fought getting it back in the cavity it came out of and screwed in place.

    BTW, again, this happened to me twice, last year in August to our Ody van and again this week, both times on very hot days. I think that if I had driven with just the fan on, no AC, for a few minutes it would have cleared out the hottest of the air and not blown the TCO.

    That is something to think about. On very hot days, when your vehicle has been sitting for a long time in the sun do not start it up with the AC on. Drive with just the fan on for at least a minute or two, and then turn the AC on.

    Good luck!
    Last edited by StanStr; 08-25-2010 at 02:05 AM. Reason: Fixed photos

  6. #5
    crv|oc Rank: Member
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    Stanstr,

    Thanks a bunch, your detailed postings were a great help to me in my almost identical predicament. My wife drives our CRV, and the other night she told me that the blower was not working. Since she told me about it, and when I've had time to look at it, it's worked intermittently- runs for a minute or two, then quits. Yesterday she was running some errands, and said it worked for a little bit, then quit and never came back on. When I got some time to tear into it today, it still was not working. I took the resistor out, opened it up, and made the following observations: Resistance between connector pins 3 & 4: 1.45 kOhms. Forward resistance (at the board level, between G & S, as you described): .923 MOhms (Is this high enough, as you mentioned it should be almost infinite?). Reverse resistance: OL (I'm using an auto-ranging digital multimeter, it's a Craftsman Professional model). Also noted an open circuit across my TCO, so I replaced the resistor, and everything seems to be working fine now. From reading the specs you posted for the TCO, I understand that it is non-resetable, so I would imagine that it only blew the very last time that the fan quit, and was intact previously when the thing was operating some times and others not. The different forward and reverse resistance measurements across the G & S pins would indicate to me that the transistor was on its way out already, then the TCO finally let go.

    I also replaced my cabin air filters while I was in there. They were filthy, and it wouldn't surprise me if their condition contributed in some way to the demise of the transistor, if the blower was having to work extra hard.

    Also, for future reference should you have to replace one of yours again, I used a ratcheting screwdriver handle (total profile height of about 5/8") to get the two screws out, and it fit pretty good. You could probably also use a 1/4" drive ratchet with a screwdriver bit in a 1/4" socket, and you would probably still have enough room.

  7. #6
    crv|oc Rank: Member
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    thermal cutoff for ac motor

    Hello, I have a 2002 crv where my ac just quit..so I searched the threads and found good info on replacing it..however the part I got was a little higher in amps than the original - anyway that fixed the motor not coming on, now its just on all the time?!? even if the fan is in the off position - any ideas??

  8. #7
    crv|oc Rank: Member
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    I'm not sure if I have the same problem but...2004 CR-V EX MT
    1) Fan is working
    2) AC is not (no cold air)

    The car was at the dealership for a cylinder head gasket replacement a few weeks ago. It's still cold here so there was no reason to turn on the AC until this week when it warmed up - that is when I found out the AC was not working.

    Could this be related to the dealership work? More importantly, how do I test for what is wrong!

    Thank you in advance.

  9. #8
    crv|oc Rank: Member
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    Quote Originally Posted by sacksyboy View Post
    I'm not sure if I have the same problem but...2004 CR-V EX MT
    1) Fan is working
    2) AC is not (no cold air)

    The car was at the dealership for a cylinder head gasket replacement a few weeks ago. It's still cold here so there was no reason to turn on the AC until this week when it warmed up - that is when I found out the AC was not working.

    Could this be related to the dealership work? More importantly, how do I test for what is wrong!

    Thank you in advance.
    Sounds suspicious, I would get on the phone with that dealership asap and mention the problem. YD

  10. #9
    crv|oc Rank: Member
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    I will but I feel unarmed not knowing what could have potentially caused it while they were working on it. They could say no, it has nothing to do with the work we did and I would be none the wiser.

  11. #10
    crv|oc Rank: Member
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    Walk-Through Questions

    Thanks StanStr.

    Couple questions:
    1. Can the transistor and TCO be tested with everything still soldered together?
    2. If so, and it is the TCO, can a new one just be soldered across the top of the board (and I guess not covered with silicon heat sink compound in this case)?

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