Sucky rear-window defroster in '03 4Runner

In my 2003 Corolla, there is no coolant control valve. When I start the engine and set fan to Full / Heat, the engine does take longer to warm up. Reason being, even with the engine thermostat closed, full coolant circulation still occures thru the heater core and so.... turning the fan ON with Max Heat will lengthen engine warm up especially in very cold weather. So... for the first 5 minutes at fast idle, leave the fan OFF.

Reply to
Philip®
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Well for me it was a balmy 10F this morning (around

-12C).

My drive is about 10 miles (17km).

The coolant actually heats up quite quickly, within a few blocks. But the controls suck big time, as they do for a co-worker with a 2003 Corolla-S. They are very inconsistent for starters, there is a ton of slop in the cables so when it is on floor/window it may be all floor, all window or somewhere in between. The most air comes out of the side window vents when it is set to floor position? When it first started to cool down this fall I noted how quickly the engine temp came up and figured this was going to be a great improvement in comfort control. Now I'm not so sure.

But even when adapting to this a using my hand to figure out where the air is going it still circulates poorly so it takes a long time to get it comfortable. This morning I had the fan on high for the whole 10 miles. Defrosting the front, side and rear windows was a challenge.

Steve

Reply to
red rover

The distribution control knob on my 2003 Corolla works as it's supposed to. There is no "slop" in the cables because they are solid wires. Furthermore, you can regulate the dash registers by rolling the thumbwheel at the end registers. Removing interior fog is a simple matter. Putting the distribution knob to the Defrost position -automatically- turns ON the A/C ... which is what dehumidifies the air ... not heat. In Defrost, my Corolla does NOT illuminate the little green light in the A/C button even though the A/C compressor is now running. SO... if you put the Heat Control knob to full HOT, then incoming air is not passed over the A/C evaporator coils which would dehumidify the air. Set temperature to medium level.

Reply to
Philip®

Sounds like you took that part of the dash apart too.

solid

Reply to
Art Begun

In order to remove the Corolla radio, you must remove the center console cover ... which is simply a matter of pulling the three control knobs, the phillips screw behind the center knob, and using a knife to simply pop out the entire console cover. Takes about 3 minutes. Then you have access to the four 10mm bolts securing the radio enclosure. Rediculously easy. But it takes an UAW worker the first time. LOL

Reply to
Philip®

Perhaps Toyota should start shipping cars partially assembled like cheap furniture.

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Reply to
Art Begun

I'm not sure where the slop is, probably the damper connections. But obviously not unique to mine as discussed with my co-worker.

My thumbwheel end registers are full open and the air flow is greatest during the floor position.

I didn't know about the AC in defrost. In my old Corolla I could manually control the 2 and use this to dehumidify, I figured this was the same in this car. I seem to recall that I've even done it in this car.

How is the air flow routed for the heat control? I recall other cars you could use the AC and full heat but probably require a damper controlled by the AC being turned on.

Steve

Reply to
red rover

You will soon be able to get a Chrysler Pacifica at IKEA.

Reply to
Philip®

There is no "slop" in the cable linkage. The cables are a single wire ... not multi wire cable.

The greatest dehumidification occurs when you first cool the incoming air followed by heating the air (results in the lowest REALITIVE humidity). Warmed air with -low relative humidity- is the most capable of absorbing moisture.

All air in the Corolla (and most others) goes thru the A/C evaporator and then to a plenum chamber where none/some/all air passes thru the heater core (temperature control knob) and then to the various outlets controlled by dampener doors. No coolant control valve is used.

Reply to
Philip®

Don't know why you believe a single wire cable cannot have slop. I had a 95 Subaru and the single wire cable for the temperature adjuster did not close the heater door completely leading the dealer to take apart the ac multiple times to figure out why did could not cool the car.

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Reply to
Art Begun

It must be a figment of your imagination because mine works great!

Reply to
CDEWITT Webtv.net

Art: What part of 'single wire' do you not understand? A solid wire in a tight fitting housing does not have slop because it cannot bend within the housing. That the housing is secured to a bracket in a manner providing precise plenum door positioning is not ... "slop."

Reply to
Philip®

Well in concession to you I had changed my wording from "slop in the cable" to just plain slop. I'm not sure how the cable attaches to the dampeners but I could picture linkages that could have some small amount of play (like a ring on a post). Or maybe the cable has come off a mounting bracket?

I'm not sure what is causing it but you seemed to have skipped over the part where I said my Corolla and a co-workers have this problem.

Thanks, I realize that.

Which is why I asked the question about how the air flow is routed (I never mentioned coolant or a control valve). If "all air goes thru the A/C evaporator and none/some/all could then pass through the heater core" then why did your earlier post state a condition where "incoming air is not passed over the A/C"?

Steve

Reply to
red rover

evaporator

Thank you for catching that error. Brain fart. I recently discovered some of these discussion threads get archived to other websites for posterity .... so it's important to minimize errors. :-) Similar to a bad credit report that follows you forever!

If the Heat Control knob is turned to full HOT but without the A/C running, there will be no dehumidification of the Fresh or Recirculated air. In the past and in lower cost models, the responsibility to turn ON the A/C for dehumidifiation purposes had been left up to the driver. In recent years the Air Flow Selector knob in all cars and trucks automatically turns ON the A/C when any windshield air outlet is selected, regardless of temperature selected. Of course, the A/C will cycle based on evaporator surface temperature. In sub freezing weather, the A/C may not come ON until the evaporator surface temperature reaches (approx) 35 degrees and then cycle normally ... otherwise the evaporator would become a complete frozen obstruction to Fresh or Recirculated air flow.

Reply to
Philip®

So what you meant to say was that there is no "slop" in the cable linkage because the cables are single wire AND IN A TIGHT FITTING HOUSING. Why don't you say what you mean.

single

Reply to
Art Begun

I spoke precisely ... but not all at once. The installments were for your benefit.

Reply to
Philip®

So is there any reason you cannot go to full hot, direct the air to the windshield and still expect dehumidification from the A/C?

I've certainly done it in the past and your earlier post made me think I should be sticking with a medium heat setting if I want the benefits of dehumidification.

Steve

Reply to
red rover

Depends on the ambient temperature. At cold start up with ambient below freezing, the A/C will not engage. And so long as the evaporator temperature remains below freezing, the A/C will not engage. So... you could not get dehumidified air even with the heater core providing heat (engine now warmed up) if inlet stays so cold. This would be a time to use Recirculate to raise inlet temperature above freezing ... then the A/C will operate. There's an amazing amount of humidity brought into the passenger compartment by a breathing body or two with melting snow on their feet and parkas. :-D

Reply to
Philip®

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