Tercel 97 heater and blower fan

I don't know the answer for sure, but in Toyotas, the blower usually pulls or sucks the air through the heater core.

Thanks, Ray O.

I'm still trying to troubleshoot that dusty and burning oil/rubber smell (a bit like deisel) when the fan turns on (recirculate). First encountered years ago. It is intermittent, and sometimes mixes in with a hot plastic smell. Had the conduit under the wipers steam cleaned, shampoo'd, the engine compartment "detailed" (basically shampoo'd), blower fan changed, and the internal air ducts subjected to an anti-mold mist treatment.

One of the reasons why the order of the blower fan and heater might be important is because I find that seals don't work so well in the cold. Household fans have this problem -- if they've sucked in frigid air from outside for a while, they start to create this burning oil smell, even though they are supposedly sealed. If the problem gets bad enough, it persists even with the incoming air is warm. Same with O-ring seals for faucets. Theys can start to leak even though they perform well when made pliable by the passage of warm water.

If the fan comes after the heater, it gets warm air except when the car is first started. That might explain the intermittency of the sooty smell. The fact that I drive in the winter with the windows down to get fresh air may further complicate when the fan gets cold air intake, though fact that the heater warms it up should minimize this as a contributor to the problem.

Dubious Dude wrote in news:flkfjj$vke$ snipped-for-privacy@aioe.org:

The blower draws air directly from the intake duct. It then pushes the air through the heater.

In other words, the heater core is downwind of the blower.

Thanks, Tegger. That would certainly explain a few things.

Check the rubber "gasket" that goes across the firewall where the hood is. If the car is burning oil by blowing it by the valve cover gasket onto the exhaust, if this seal is loose or broken the fan will suck the smell in through the vent.

Of course, check the valve cover gasket, too! ;) Also, see if the oil pan is loose or other leaks.

Tegger is more familiar with Tercels than I am so I'd go with his description rather than mine here.

Does the smell change - get more or less noticeable when the system is on recirculate rather than on fresh? If so, check the interior recirculate intake. Another potential source of smell is debris accumulated on the blower resistors. A very gentle wipe with alcohol or tuner cleaner might clean them up.

Yes, that was one of the things I checked when troubleshooting the problem a few years earlier. Had a few professionals look at it too.

As well, I've given up trying to troubleshoot the problem in its entirety, and am focusing on troubleshooting it in recirculation mode as a start. Eliminates some unknowns.

Again, done early on.

Appreciate the suggestions nevertheless.

Over the years, I've tried exhaustively to characterize the repeatable circumstances under which the different variations of the smell occur, but nothing conclusive aside from the fact that it occurs when the heater is on and fan is on. Since everything else seemed inconclusive, I've focused troubleshooting efforts on the case where the air is in recirculate. Otherwise, it gets very confusing, with all the external smells (including Krown smell from the engine compartment).

Your comment about the recirculation intake is interesting. I've been leafing through an 89 Toyota Repair manual, an 87 thru 94 Haynes Tercel manual, the vehicle owners manual, and web images trying to get a clearer picture of where things are. I have to admit that it isn't clear where are the intakes for recirculation. Manuals are great for showing close-up views, but only so-so for global views (as I found out when trying to find whether heater is downwind from fan). Haynes also has a heater and air conditioning manual, but amazon reviews have shown it to be somewhat generic. If it is like the manuals I have, most of it focuses on the A/C system.

I'm not too keen on getting detailed manuals at this time, since I've lived in a high-rise for a long time and found it inconducive to working on cars. To get a bit more familiar with things through hands-on, I'm considering asking a friend with an unheated home garage who lives in the city outskirts, but I'd be stuck in the boonies if I didn't finish it all in one day (a real possibility, since I'm quite inexperienced working with cars).

For now, I'm trying to get insight into the possible causes so that I can task my mechanic to do further investigation. I'll keep your suggestion of the blower resistors in mind for that purpose. Hopefully, it isn't as arduous as accessing the heater, since that apparently requires disassembling the dash, and would put it into the hundreds of dollars. Despite that, I'm seriously considering having this done simply because everything else has been tried.

Note that I already had him replace the blower fan (new but not OEM, some manufacturer name sounding like "Nader") and he already used pressurized air to test for dust in the ducts before that. Not sure if this would rule out the blower resistors. He also sees no characteristic dampness on the heater which might indicate a pinhole leak.

One of the characteristics of the smell is...imagine walking into a tire shop, or a shop with lots of rubber. Pretty soon, you taste the bitter rubber smell in back of your throat. Now add in slight saltiness and the *intermittent* musty sensation that you might have when walking into a room in which plaster dust has been stirred up. Sometimes, you feel slight stinging in the eyes. That's the best that I can describe it.

The resistors for the blower are downstream from the blower itself. Air from the blower cools the resistors, which heat up at any speed other than high. Ease (or difficulty, depending on the application and one's point of view) of access is roughly the same as accessing the blower motor. The blower motor is under the passenger side of the dashboard.

Since Krown is a product sold in Canada, I assume that the weather is rather cool where you live and so working outside this time of year is not very comfortable.

The rubber smell could be from a buildup of something on the resistors. The intermittent musty smell could be from a buildup of condensation in the system.

I would start by checking the resistors.

That's good to hear, since the blower fan is supposedly easy to access.

Yes, you're right. I think it recently went as low as -25C (-12F), and windchill went as low as -32C (-26F). Of course, there's no windchill inside the garage, though I'm not sure how humidity affects the feels-like temperature.

Thanks, Ray. I will bring that up, along with a re-examination of the firewall seals. The latter because perhaps Krown has seeped in. After all, it is suppose to seep everywhere, and whatever thing is getting into the internal vent/heating system has to come from somewhere. In your experience, what kind of gunk typically gets onto the blower resistors?

Blower motors are usually a lot easier to reach than the heater cores.

Stay warm!

Normally, the gunk on the blower resistors is just lint and stuff from inside the car, but I was thinking that some Krown may have seeped in as a vapor and coated the resistors and fan.

Thanks again, Ray.

You're welcome!

Dubious Dude wrote in news:flp40a$ro7$ snipped-for-privacy@aioe.org:

The recirc intake is at the side of the blower housing, inside the passenger compartment, behind the glove box. The intake for fresh air is at the top of the blower housing, drawing air through the hole in the cowl.

When you switch between fresh and recirc, you are opening and closing a big flap that either exposes the fresh intake at the top (covering the recirc intake), or opens the recirc intake on the side (covering the fresh intake).

I find it hard to see how the blower resistor could cause any sort of smell. The resistor is an electronic device that consists of several coils of resistor wire set into a plastic plate. These control the fan speeds. There is a bit of hard plastic applied to the coils to keep them from vibrating.

If you raise the hood, do smell the same thing in the engine compartment? Has anybody recently added sealer of some sort anywhere to prevent water leakage into the interior?

There is nothing that I know of in the vent tract which would cause such a smell. The only rubber used is a thick, soft urethane foam which eventually dries up and gets powdery.

A mossy A/C evaporator usually smells like dirty socks. I don't associate that with rubber.

What I can see happening is a leaky heater core. Old coolant smells rubbery. It also smells sweet. Engine cold, take off the rad cap. Take a whiff of the fluid inside the rad. Smell like what you smell in the interior?

Dubious Dude wrote in news:flphch$ld$ snipped-for-privacy@aioe.org:

Krown is not applied to the interior or to the cowl. And Krown has its own odor, which is nothing like rubber.

I agree. I'm just ready to entertain remote possibilities at this point, even if I can't explain all aspects of them.

For example, someone mentioned that a pre-2001 Krown formula attacked old model Toyota firewall seals. Since I'm not the original owner, that could have happened for this car. This is no longer a problem, probably due to reformulation of Krown. However, there might still be old formula impregnating the (possibly) compromised seals, so the new Krown might simply carry some of the old-Krown/seal-rubber mixture through the firewall. Kind of a stretch of rationalization, I know.

On the other hand, if the problem of Krown attacking firewall seals is due to different rubber for the seals on the newer model Toyotas, then my Tercel will not have benefited. I still need to inquire with Krown and Toyota about this.

Thanks for that, Tegger.

Hmm. Having a bit of an electronics background, I would tend to agree. If any of that material was the cause, a whole lot of people would be complaining about the same thing.

It's a bit hard to tell because of overwhelming smells under the hood (Krown everywhere). The symptoms described above are not strong. The delayed effect (coughing for 1-2 days) are the real problem. Long trips could lead to couging for over a week.

Not unless my mechanic did it without noting it. I will ask. This problem has persisted for years, however. The engine was changed twice within months back then. It is hard to know whether the problem existed before that, since I might have simply attributed it to personal pulminary problems, and suddenly realized its association with the car after being away from it during the repairs. It certainly became more noticable afterward.

Could it be the powder? Though one would expect any particles likely to be made airborne would have been evacuated from the tube within a short while of starting up the fan i.e. a transient problem at start-up. The problem I describe is quite persistent.

I did try this years back, and they did not smell similar. I will try it again.

Thanks for the thoughts, Tegger.

Dubious Dude wrote in news:flsa9f$kan$ snipped-for-privacy@aioe.org:

Been using Krown for a decade on two vehicles. First I've heard of compromised firewall seals.

Krown does damage some rubber, but firewall grommets are not among the usual victims.