Broken Rear AC. Grrr...

[reds2k1]

Thank you for the link to the post. Much appreciated.

It's not that I can't use the SEARCH feature, but the thing with searching is knowing what to type in the Search field.

Originally Posted by Smeddy2

Just googled "acura mdx front a/c repair" and this is the first thing that came up.

1st gen MDX Front AC fix

[Smeddy2]

Yeah it can be tricky sometimes...no worries.

[barrelled1979]

Just wanted to say thanks to everyone, just fixed my rear a/c with all of your help...well at least most of your help

[woof]

Well...

...I never thought I'd need it but here I am. My rear HVAC unit stopped working today. I'm almost 100% sure it's a broken thermal fuse. Just thought I'd pop in to subscribe for now. I'll have to buy a fuse and do some soldering sometime in the near future when I get a chance!

[woof]

Just an update that I decided to order a couple of thermal cutoffs from Digi-Key as well. They were 86¢ each but shipping is still $8 to Canada. Interesting to see that the shipping rate to Canada hasn't changed over the years since it's been $8 since the early pages of this thread!

Is it coincidence that I had to re-solder a few connections on my Daytime Running Light module recently too (you guys in the U.S. are going,"Huh?" at this point!)? I guess over time the solder points just crack but I find it funny that this will be 2 solder issues in a relatively short span of time.

[TexasHonda]

Any solder jt that gets warm and then cools is subject to fatigue cracking. Solder is not too good in fatigue loading.

good luck

[Warzau]

I don't think so much it's solder itself in that particular environment, but the fact it prob lead free solder.

[woof]

Do you suppose they used lead-free solder back in the early 2000s on these cars? I Googled typical solder joint failures and came across this short summary:

Solder Joint Failures

Solder joint failures occur for various reasons: 1) poor solder joint design; 2) poor solder joint processing; 3) solder material issues; 4) excessive stresses applied to the solder joints, etc.. In general, however, solder joint failures are simply classified in terms of the nature of the stresses that caused them, as well as the manner in which the solder joints fail.

Most solder joint failures fall under three major categories: 1) tensile fracture due to stress overloading, which is short-term; 2) creep failure due to the application of a long-term, permanent load; and 3) fatigue failure due to the application of cyclical stresses. Of course, more than one of these stresses can act on a solder joint in a given situation, so solder joint failure analysis can be challenging at times. Add to this the fact that solder joint degradation due to other factors such as corrosion can occur.

[woof]

UPDATE:

I ordered 2 thermal cutoffs on Thursday February 14th, 2013 from Digi-Key and received the items the next day! I only got around to working on the car Sunday February 17th, but everything went pretty well (thanks to the wealth of information on this site) and now my rear HVAC blower is back in full working order once again.

I ended up insulating the thermal cutoff with polyolefin heat shrink tubing then applying an anti-oxidant compound similar to thermal grease at the interface between the transistor assembly and the heat sink. While I had the lower panel open, as others have recommended, I picked off the enormous dust build-up at the rear HVAC filter/screen. Didn't have to use a vacuum since the layer of dust was pretty solidly packed together. Ewww.

[itsboosting]

just got this fixed thanks to this thread! awesome!

[Hawkeye83]

Just replaced the thermal fuse. Went from no blower to blower always on high. Green Rear Manual control light is on in the front controls. When I push that, I can switch from the top vents to the floor vents using the rear controls, but the fan speed never changes and I cannot get the blower to ever turn off. It turns on as soon as the key is turned. When I turn the AC completely off, the rear blower stays on full blast. For now, I have the power unplugged to the blower so it is always off.

Do you think a new transistor assembly is needed? I have read elsewhere that when it fails, it can fail closed.

When I replaced the thermal fuse, I just wrapped the wires with electrical tape...I don't THINK there is a short, but I'm not 100% sure. I don't have any of the insulator sleeves.

[Hawkeye83]

Nevermind. I jumpered it out with a piece of speaker wire, and it's working great now Thanks for all the informative posts here!

[natesezgoblue]

hmmmm..so i jumped the circut and it didnt work. Fuses are good and ligts on the unit come on. Anyone know how to test the fan without having to pull it out?

[Gryder]

The MDXer's on this board are awesome! Just did the clean screen and replaced the transister. 1/2 hour job and "Houston we have the Rear A/C on again!"

Thanks so much!