***IN THE MAKING, DONT DELETE*** So heres how you would fix your faulty heater control unit if it does fail. This fix takes longer but will last longer that just doing the short fix. Basicly the problem is that the soldered connections on the unit get tiny littly hairline cracks in them, meaning that theres no connection. This is due to the fact that your car is 20 freaking years old. So i'll start with the removal of the unit. You have to remove the glove box and dash under the stearing wheel first. Then the center consol, and then the center dash. So basicly, remove everything except for the top dash. Once thats all removed, remove the radio and then you can take out the few screws that hold the heater control unit in. Now your gonna have to wrestle the unit out, but be careful, dont forget to unplug it before you wrestle. Once the unit is out, you can remove the 4 screws that hold the smaller section in. Then you can fidle with it to get it out. The larger board has 2 screws that hold it in. When fidling this board out, you kindof have to be harsh because the buttons clip in, so you kindof have to pull. YOU TECHNICALY DONT HAVE TO REMOVE THE BIGGER BOARD. Once the smaller board is remove, you can go and get a soldering pen. I got my at radio shack for 8 USD. You only need a 25 watt. When using the gun, becareful, its very hot, give it a good 5 min to warm up all the way. When its warmed up, firmly place it on the old solder to heat it up and liquidize, making the cracks go by by. Be patiante, it takes alot of time, just dont try and hurry up, one screw up and ur screwed. Noone really knows which solder controls the lever that opens and closes the vents. I do know that when soldering that i could only see 1 solder with a crack in it. I will post a pic of that. Good luck Pics later
oh.....I have to flip the valve in the engine bay manually but that's because a little plastic piece is broken at the servo motor and won't push the cable
Your on the right track here. I will just clear up a few minor techincal things about solder joints and soldering. So please nobody take offense. There is a couple of failures when it comes to solder joints. 1. "Cold-solder" joints, this is when not enough heat was applied to both the board and the wire or connector being soldered and solder doest "flow" properly. Now these types of joints can fail within days or years. They have a dull porus look to them. 2. Physical failure. Due to expansion and contraction(getting hot/cold) These will have hairline cracks or they may not. The joint could be bad inside the solder. Solder itself is made of tin/lead usuall 60% Tin 40% Lead. The two common solders for electronics is 60/40 or 63/37 60/40 melts around 390F and 63/37 melts around 361F There is a core inside of solder. It is flux usually made of rosin. The rosin inside the solder acts a flux and cleans as you solder, but it can only accomidate for minor oxidation/dirt. There is also what is referred to as Silver solder which is a Silver/Tin mixture and is used in high heat applications. ie Amplifiers etc. Ok. Now some how-to tips on soldering. The joints/wire/parts you are trying to solder need to be nice and clean. If its not youll never get a good connection. Make sure you have a decent iron with a clean tinned tip.(tinned means it has a coating of solder on the tip) Use only the correct size diameter solder for what you trying to solder. Use the proper type and size of solder Rosin core is used for all electronics and acid core/or no core is typically used for plumbing. You wont need real large solder for doing electronics. Typical diameter for electronics is .025-.040 Make sure you heat the both side of what you are trying to solder. Apply the solder to the joint, not the iron. A typical solder joint will take less than 5 seconds from the time you set the tip on the joint to when you apply solder. Solder will just flow on a properly heated connection. Dropping "blobs" of solder on a joint is no good and will not make a good electical connection. ALWAYS!!!! Desolder a joint if you going to resolder it. Remove as much of the old solder as possible. Using either a de-soldering tool or solder wick. Reheating solder only weakens it and add contaminants only to create future problems. Some soldering Myths. More solder the better. Not true. Use just enough to cover the joint. The bigger/more power/heat the better. Not true. Heat will distroy componants and circuit boards. 25-40W iron is plenty for most circuit work. Soldering guns are usually 300-500W and should only be used to solder large componants and large wires together 16AWG and larger. Soldering Guns take a long time to warm up. Not true. A properly setup Soldering Gun will be ready to solder in around 5 seconds from pulling the trigger. What happens is the copper tip gets oxidized and does not make a good connetion to the lugs. Most of the time simply loosening and tighted the set screws on a soldering gun will restore the connection. Irons do take a few minutes to warm up and cool down. This is only some "brief" info on soldering. This is like anything else and takes practice. Ive been soldering for 17 years now and its almost an artform. Here are some good links I dug up on it. http://www.epemag.wimborne.co.uk/solderfaq.htm http://www.aaroncake.net/electronics/solder.htm Ok Im off my soapbox now have fun and dont burn yourself.
Here's the write-up as previously discussed on www.toyotacelicaonline.com Direct link: http://www.toyotacelicaonline.com/board ... heater+ifx
Please could you update the link/pics? I've tried 2 units and still no heat or economy settings. Beginning to suspect stuffed servo or stuck flaps
^Yeah, that site is down. Go here instead: http://alltrac.net/phpBB2/viewtopic.php?t=30527 viewtopic.php?f=48&t=237
I can't see how disconnecting the cable is a long "fix"? Is the servo on top of the computer or under the dash? I have RHD and can't see anything I can feel a cover above the computer but not into wasting time ripping all that stuff out
It's not. Please see the article: disconnecting the cable is the "Quick Fix" Servo is on top of the ECU on LHD, should be same for RHD.
Ok, it's all starting toi make sense now Pity nobody mentions removing the computer first, I can't get my hand in there I have aleady re-solderded 2 units - no faults on either and still no joy Thanks
^You don't have to remove the computer in either of those "fixes". Yes, the servos are located on top of the ECU, but you are just taking out the heater control panel for resoldering. That panel controls the servos. If you're still not getting heat, it could simply be that you've missed a bad connection or of course, there may be other issues....? If you open the flaps via the "Quick Fix" method, do you get heat?
