Heat actuator - P/N 52474810

[chris_kucia]

Did some work on the truck yesterday (added remote start and heated seats - very cool). While I had the seats out and had plenty of extra room to work, I took the heat mix actuator out and took it apart.

 

How it works: Inside are a standard DC motor (not a stepper), a set of reducing gears and a small blue gear that appears to have a magnetic pickup. The final actuating gear has a detent tab on it that fits in a semi-circular groove on the outside of the case.

 

Problems:

 

1) The yellow grease inside has become more like yellow wax. Really gums up the works

 

2) The primary gear off the worm drive on the motor has a hole that is too snug on the shaft. It was very tight.

 

3) Something (on mine) is wrong with the actuator (more below).

 

I cleaned out the grease and used some light oil on the gears. Also ran a drill through the primary gear to free it up. So far so good.

 

However, the overall problem with the actuator is that there appears to be something wrong with the feedback off the blue encoder gear. When stepping between any setting besides full cold and full heat, the motor bumps the actuator a small amount. However, at full cold or full hot, the motor runs much longer and sometimes appears to go through some sort of initialization routine - at the end it stops, backs up a tiny bit, goes forward a tiny bit, and stops.

 

The problem is that when you pick full hot, it appears that the encoder isn't working properly. The motor then runs so far that the main gear hits the detent. This overtorques all the internal gears to the point that the mechanism jams up.

 

From my observations, it appears that either the HVAC controller or the actuator sometimes (but perhaps not always) go through a reinitialize routine if the systems is on full cold at startup, that backs the motor down to reset the cold side detent. After a couple of these, sometimes its enough to free up the mechanism, and everything works OK.

 

I tried playing around with the position of the encoder gear, but since it appears to reinitialize at full-cold, it resets back to the old way of jamming up at full hot.

 

 

If you're having this problem, my suggestion is (once it starts working again) to never turn the mix dial all the way to full hot. As long as you never hit that last setting on the dial, the system will work fine. Even if you just click on and off on the full hot, the motor will overrun and jam the mechanism.

 

YMMV, but you might be able to get away with getting the gunky grease out and reaming the primary gear if yours is sticking because of those problems. I don't see a way around the overrunning and I'm going to order a new one.

 

 

Rant:

I love my truck, and I am a die-hard GM customer, but WTH is going on with this company? They've been making cars and trucks for 100 years now and they can't get a simple heater actuator right? Its not like this is the only vehicle that has one. I don't know if its bean counting, or poor vendor selection, bad design, or what, but after awhile this stuff starts to tick me off.

 

Truly, I could understand if the part wore out mechanically. I might even be cool with the grease hardening, but the overrunning thing really bugs me, and having to pay for the darn thing myself, which is ridiculously expensive for what it is, even discounted, just makes it worse.

 

 

I've always tried to overlook "little" things like this, because overall I get good service and service life from my GM cars and trucks, and I meticulously maintain them. However, thinking back over the years, it seems every GM vehicle I've owned has had a handful or two of parts that failed because of poor design, lousy quality, or other reasons that fall into the "why did they do this?" category. They're always expensive, and more often than not they are parts that should't be unique to the vehicle (I could cut them a little slack for things like that).

 

On my truck, I've replaced the driveshaft yoke (something that's had to have been on GM vehicles for what, 75 years?), the intermediate steering shaft (ditto), had to wrestle with the trans pan drain bolt (ditto), had the leaf spring insulators jump off, replaced the tailgate cables (how many years has GM been building pickups?) and now the heater actuator. Of course, I've done plenty of maintenance, but these are things that had to be replaced because they were designed badly.

 

Sometimes, it really makes me wonder if my brand loyalty is misplaced.

 

(end rant)

[PaulieK]

I understand and agree with your rant in many area's. For instance my truck has in my oppinion terrible fit and finish for a 44 thousand dollar vehicle. The bottom windshield molding has a gap of over a quarter of an inch at the corner of the windshild on the drivers side. The reason? Cheap plastic that has either warped in the cold or a total lack of a proper anchor on that corner, at least the passenger side has the radio antenna to hold it tightly down. I think it is the little things that piss me off the most. But remember that the problems we have with our GM vehicles are not isolated. These idiotic problems plaque all motor vehicle manufacturers.

[chris_kucia]

But remember that the problems we have with our GM vehicles are not isolated. These idiotic problems plaque all motor vehicle manufacturers.

 

<{POST_SNAPBACK}>

 

 

 

Yeah, I know. They're all using a lot of the same suppliers.

 

Thing is, I'm probably more of a GM-cheerleader than most. Other than one Chrysler (Sebring ragtop), I've owned a string of GM vehicles of all shapes and sizes. I do all my own mechanical work, and I'm big on proactive maintenance. I really like GM cars to the point that there are very few other manufacturers I would consider.

 

So, if I'm starting to get disillusioned, imagine what the average joe, with a GM vehicle out of warranty, paying a dealer to put in gm parts at retail, feels like. Even under warranty, I'd have averaged one trip per year over the life of my vehicle, fixing things that should not have broken in the first place.

 

 

I've never bought a new car - I always buy used because after about 3 years, you can get a vehicle for around 1/2 of the new list price, and I figure that most of the obvious defects will get fixed under warranty in those first three years. Looks like that's not the case with my truck, but still, I think its a good strategy.

 

For the last few years, I've been in a position where I could afford a new car or truck, but I'm really gun-shy about it. Even with the sales, new cars are very expensive compared to used, and with a new vehicle under warranty, I'm stuck with going to the dealer to get things fixed unless I want to pay for it myself.

 

I'd like to be a new car GM customer, but it won't be for awhile. Maybe if the next used GM I buy is better, I'll consider it on the next car. Hopefully there will be a GM to buy from by then.

[Elwood 2000]

I feel that a lot of these problems exist because customers insist on many "gizmos" and fancy things. Digital thermostats, power folding mirrors, etc. While these things are great, and I do love them myself, they cost money. Two things they try to do is keep cost down with all these additions and weight. Combine those and we get cheap, lightweight plastic parts from inexpensive manufacturers that will work all day for 25 cents. Assemble all these cheap parts and this is what we drive today.

 

It is sad, but it is my thoughts. Look at a 1979 Chevrolet and while it is minus all the bells and whistles, I have never had HVAC problems with one like you just described.

 

 

Don't get me wrong, I love the new Chevy's and it would be hard to go back to a 1979 truck as a daily driver after being in a current model, but something has to give. I think quality on some of these components is where the "giving" is at. Unfortunately, I feel this is true for just about all manufacturers.

 

 

 

Just my thoughts.

[2004GMC1500CC]

But remember that the problems we have with our GM vehicles are not isolated. These idiotic problems plaque all motor vehicle manufacturers.

 

<{POST_SNAPBACK}>

 

 

 

Yeah, I know. They're all using a lot of the same suppliers.

 

Thing is, I'm probably more of a GM-cheerleader than most. Other than one Chrysler (Sebring ragtop), I've owned a string of GM vehicles of all shapes and sizes. I do all my own mechanical work, and I'm big on proactive maintenance. I really like GM cars to the point that there are very few other manufacturers I would consider.

 

So, if I'm starting to get disillusioned, imagine what the average joe, with a GM vehicle out of warranty, paying a dealer to put in gm parts at retail, feels like. Even under warranty, I'd have averaged one trip per year over the life of my vehicle, fixing things that should not have broken in the first place.

 

 

I've never bought a new car - I always buy used because after about 3 years, you can get a vehicle for around 1/2 of the new list price, and I figure that most of the obvious defects will get fixed under warranty in those first three years. Looks like that's not the case with my truck, but still, I think its a good strategy.

 

For the last few years, I've been in a position where I could afford a new car or truck, but I'm really gun-shy about it. Even with the sales, new cars are very expensive compared to used, and with a new vehicle under warranty, I'm stuck with going to the dealer to get things fixed unless I want to pay for it myself.

 

I'd like to be a new car GM customer, but it won't be for awhile. Maybe if the next used GM I buy is better, I'll consider it on the next car. Hopefully there will be a GM to buy from by then.

 

<{POST_SNAPBACK}>

 

 

 

 

Maybe its your mechanic?

[chris_kucia]

Maybe its your mechanic?

 

<{POST_SNAPBACK}>

 

 

 

Sort of like the adage "A lawyer who represents himself has a fool for a client"?

 

"A guy who works on his own car has a fool for a mechanic"

[Jansen]

I echo the concerns here. When you look at what is described it is no wonder that GM is going out of business. I think a back on my truck :

 

- Rear Door panel replaced (warped)

- Front Apillar trim replaced (faded, warped)

- Rear diff fixed (was leaking after 1000 miles, WTF????)

- Onstar unit flashes Red (going in on the 26th of December)

- Hood Misaligned (no gap on driver's side)

- Tailgate straps replaced

- Piston slap

- Driver's side heated mirror no longer works

 

This is all in the 1st year of ownership!! What the hell can I expect for the rest of the trucks life? The truck had 095 miles on when I bought it. How can all the above be possible on a truck that had a sticker price of $35,000. Don't get me wrong, I'm the FOOL who (thankfully) didn't pay that much for it, but I did buy it. I should have learned my lesson on U.S. vehicles with my 2004 F150 NBS. I was a diehard "buy American" type person. I had a 2004 F150 NBS, guess what I had to lemon law it (totally hosed truck). Now the GMC is doing better but with this laundry list, when the truck is out of warranty, I'm out of the GMC. I'm sorry to say it but Toyota is going to get my business. GMC, Ford, all of the US manufacturers need to do what Toyota does. Toyota picks one vendor and they work with that vendor to keep prices down and quality up. They don't float from vendor to vendor putting cheap crap on vehicles because someone can design a less qualified part for less money. GM knew Toyota was coming and they said, hey we have a reputation lets build SH** and float on the reputation. Sorry, Toyota builds a lot of vehicles in the US, so I consider them a US made vehicle. My truck was built in Canada for pete's sake. Next time, I'm buying a Toyota Tundra built in the US.

 

Sorry for the Rant.

 

Jansen

[asilverblazer]

I imagine it will be flawless truck with 0 problems like everthing else God, I mean Toyota craps out there factories hairy brown eye.

[Jansen]

I would expect it to have a few problems. However, I would bet any amount of money that it wouldn't have nearly the amount of problems as any US vehicle of any type. My friend bought his Tundra at the same time I bought my GMC and he did have a fuel pump failure. As of today, he has had no other issues. But you know, when you see people with Toyotas that consistently go over 150K and have nearly zero cost (other than routine maintenence), then you start to consider your truck going to the delearship 3 times in less than one calendar year, it starts to to get real tiring. I just think the U.S. manufactures are still stuck in the lets-screw-our-customer mode and have driven themselves so far down that road that they can't recover. Back when the U.S. was the king they started this low quality crap to fleece even more money from the consumer, now they are paying for it. I just wish it was the executives, who made these decisions, that were paying for it and not the people on the line.

 

Jansen

[CapitalTruck]

I have been trying to get my parents to buy a GM vehicle. They haven't owned an American vehicle since the mid 70's when they were f***** by a Buick. I'm trying to get them into a Malibu Maxx. So today, I'm driving my dad around in my 04 Silverado (bought it brand new, now have 31,000 miles on it) and there is a buzz in the door, the air mixing door (as described above) is clicking (really annoys the piss out of me), engine has light spark knock, and then, to top it off, the d*** instrument panel bulb behind the voltmeter burned out. It just really pissed me off. How am I supposed to get him to buy UAW/American when my 04 model is already exhibiting signs of fatigue? My warranty ends in 5k miles and I'm freaking out. I just needed to let off some steam. I would never do anything crazy and buy an imported car/truck or anything like that. But Jesus, why can't a domestic make do me right?