Heater/blower resistor pack

[autobody]

Hi all, some help please. I have a SC with AC. I know my heater resistor pack needs replacing as it only works on full speed.

I got a used one from eBay, went to fit it and the wiring plug does not fit. I have 6 pin plug on my car. The replacment resistor pack I have is 4 plug only, was from a UK spec mk1b.

Looks like the import has different resistor packs. Can some one confirm I have the correct part number, from my research it's the same part number showing for both UK mkb and import SC with AC and climate control. Going to order one tomorrow from Toyota but they are unable to confirm the part number.

See pic below:

Here is my heating control:



Here is the six pin connector and resistor pack:



Both resistor packs side by side, left one is the 6 pin with extra resistor taken out of my car, the right one is a uk mk1b:






Here is the part number I am getting from the online system with my car details, 87138-17010. This looks to me the same part number for the UK spec mk1b which I have already and is 4 pin only. Not sure if this is right.

[kaiowas]

Where the part is listed on your screenshot there are 2 part numbers listed. when I look on ToyoDiy I see the same 2 part numbers but the description text is in English:

87138-17030 - [No description text] - Presumably the standard item that you have just bought
88635-17030 - "W/Automatic air conditioner" - Presumably the one you have fitted to your car that you need.

[autobody]

Thanks for the info, and the part number you suggested was correct.

Unfortunately part is discontinued

Does anyone have a spare knocking about? If not how easy is it to fix?

[Lauren]

I've asked Mark to have a look as he may have some in his box of bits, just not sure whether he saved the resistor pack.

He reckons the alternative is to make up something that will work with the right wire and finding the right resistor. But he'll have a look and I'll let you know.

[autobody]

Thanks Lauren, great help and much appreciated.

All the wires on my look in good condition and can't see any sign of them being snapped. Must be the White resistor that's gone?

[Lauren]

Mark has had a look, unfortunately he has an NA one, but not the six pin one you are looking for.

Sorry.

Unless you can work out where your one has failed and replace the wire, but it'll need to be right of course resistance wise. Or perhaps it's the resistor, but it's finding what the resistance is that might be the difficult part.

[kaiowas]

I'd be surprised if there isn't a suitable alternative that's more readily available, although I'm not sure how easy it'll be identify one. A good starting point might be to find a Toyota of similar vintage that was sold in the UK with a/c in decent numbers

[autobody]

Thanks for checking Lauren. All the wires look good. The resistor has the same marking as the 4 pin one so I could in theory swap them over and hope for the best.

The plug is 6 pin but only 5 of them are being used. I found a Toyota supra 89 model to have 5 pin with AC so could try that too. Hopefully get this sorted before the winter comes.

[jimi]

Use a multi-meter to test the continuity of the resistor and coils to see which coil/connection is faulty(if any) they should all be low resistance (a few ohms), the resistor pack may be OK and the fault lie elsewhere (switch/wiring)

[autobody]

I think your right Jimi, heater only works on full and non of the other speeds.

But not done any testing. I never used a multi meter before. My mate has one. So will get the now. And start watching some YouTube videos.

Do you know which pins to bridge? (Not sure if that's the correct terminology or not).

[jimi]

Unfortunately not with the 6 pin pack, none of the drawingz I have sbow the 6 pin only the 4 pin. If you have the pack out it is relatively easy to figure it out by looking at either side to see which pins the coils/resistor are connected across

[autobody]

No problem, okay so this is how I have set up the meter:



And as we are unsure of the pins, here is a pic with numbers on it. I've just numbered them for reference. Number 6 does not connect to anything on the plug.



These are the ones with are connected :

Pin 1 & 2
2&3
3&4
5&6

1&6 have a white resistor connected.

I will post in a min about results and which pin I bridged.

Appreciated your help on this Jimi.

[autobody]

Some readings. All of which I get some current. The numbers don't stay still much but when they do, this is what is displaying. Am thinking the resistor pack is good?

Pin 1 & 2 = 0.7
2&3 = 1.0
3&4 = 1.3
5&6 = 0.6

1&6 = 0 but only resistor is connect here and not the round wires.

Connected these together too:

1 & 2 =0.7
1&3 = 1.4
1&4 = 2.3

[jimi]

They all look like the kind of values I would expect. But the resistor value (if that's what it is) seems very low, but that may just be the meter.
Try putting the meter across the wires of the resistor and see what you get. Compare it with the 4 pin one you have. What markings are on it (the resistor)?

[autobody]

Ah I see what you getting at. The White resistor thing is not beeping on the 6 pin plug, so it's not reading at all.

However the 4 pin one is, it's about 4.0

The both have the same markings but very slight number change on them, not sure what they mean. Here is the 4 pin. On the 6 pin all same apart from F1 is J2.

145oC F1
7A 125V
025 (image of a triangle)
UMI

[jimi]

A
145oC F1
7A 125V
025 (image of a triangle)
UMI

That helps, it's not a resistor after all, it's a 7 amp thermal cutoff (fuse) that will blow at 145°C.
It's there as a safety device which will cut the power if there's no (or not enough) airflow across the resistor pack i.e. fan running on a 2 or 3 speed setting and no airflow.
Switch your meter to the 2K range and test the fuse again (both across the pins and across the leads) if the meter reads 0 or very low ohms it's OK if the meter reads OL then the fuse has blown. If it has blown you could use the one from the 4 pin pack to replace it or try find a replacement which may prove difficult, unfortunately it's a fairly uncommon specification.
As a test (and only as a test) you could short it out with a piece of wire and see if the fan runs OK on all speeds.

[autobody]

So just this min I did as you wrote. Changed meter to 2 k and the working 4 pin was reading very low. The non working 6 pin was OL. So then I connected the wire from the working fuse and connected to the non working fuse.

Fitted it to the car to test and it worked. I had all heater levels working


Don't think I would have tested it like you suggested so thanks for the input and help getting to the bottom of this. We now know I need a fuse. Had a sick look and can't see any with the same spec, some are very close.

I could remove the 4pin fuse and use a soldering iron and hope it sticks.

Here are some pic of what I did.



I can't see much or any solder on here. Do you think it's a soldering iron job?



Will let all know once the transplant has been successful.

[jimi]

I only guided you in the best method of checking it (one of the benefits of 45+ years experience as an electrician) You did the work and found the problem well done.
From the look of the last pic it's spot welded in place rather than soldered. Those coils can get very hot in use (which is why they are positioned in the airflow) possibly hot enough to melt solder which is why they are normally spot welded.
Having said that I think you will get away with soldering a replacement in.
What I would do is to cut the blown fuse out but leave as much of the wire in place as you can. Cut the good fuse out leaving as much wire attached as possible. Clean then tin all the wires before attempting to solder the good fuse to the old wires you have left in place. Bear in mind it's a thermal fuse so try not to get it too hot, leaving long wires in place will help to keep the heat away from the fuse. Or you could try crimping the wires together using uninsulated crimps.
Before putting the pack in place bend the fuse leads so that it sits away from the coils and any heat they generate.
This one is probably as close as your going to get http://uk.rs-online.com/web/p/non-reset ... s/7127294/

[autobody]

It works

I took the fuse off the 4 pin and used it to replace the blown one. Just tested it and had it running for about 20 min. All speeds work. Feels great fixing a problem without spending anything.

Thanks Jimi for guiding me through the process.

[jimi]

No worries, only to happy to help
It's great when you successfully trace a fault and the fix costs you nothing