Builds Live in Texas, drive a pickup: HDJ79 single cab build

[RHINO]

i'll go have a look, its still two wire.

i dont want to sound condesending or anything, and i'm no expert, but i learned alot about a/c systems one year so just in case you DO know this maybe it'll help others

our simple trucks use the thermister to cycle the compressor on and off within limits toyota set, i dont know those numbers but the limits are just a value to turn the compressor on and then shut it down before freeze up, but thats all it does, if you want less cold air you either turn the blower down or start mixing in warm air.

on newer computer controlled cars it uses the complete resistance reading and can cycle the compressor at different rates to regulate an in cab air temp you set, heck they even have multiple thermisters to have two different temp settings on each side of the cabin.

so i guess a newer thermister has replaced the older one, but i have to assume (operative word here) that the values are still set in our rigs little t-rex sized computer and the newer thermister will still work as the switch since its just seeing a low and high value.

oh, i just remembered there are two types of thermisters, a negative and a positive, i dont know if toyota changed what they use, but i suppose thats the only thing you really want to check,,,, its just like it sounds, one uses a falling resistance while the latter uses a rising restance.

 

[bottombracket]

It’ll be easy enough to track down @davegonz and my 74 series, which has the old style thermistor. We can ohn out the resistance values for each one to confirm…but agreed, both are doing the same job in a very simple a/c system.

 

[bottombracket]

So I learned a lot tonight.

I retrieved a cooler harness out of a friend’s HZJ79. Guess what? It fits. Also, three years ago, I (incorrectly) ordered the old style AC amplifier. It fits. I have a cooler sub harness on order from Dave Stedman.

 

[bottombracket]

I broke out the FSM, and found the resistance values for the old style thermistor.

The test procedure is to remove the thermistor, put it into ice water, and check its resistance over a range of temperatures. I’ll get to that, but I just took a reading at 71° ambient air temperature. 1401 ohms for the new style thermistor. The old style thermistor measured 1513 ohms. Same ballpark. Promising.

 

[bottombracket]

Next problem:

I realized that the blower motor and heater blower resistor plugs were also different post 1/2007. Fark.

I grabbed my 2018 HZJ79 wiring harness and plugged it in. As expected, it fits. I need to get my hands on an EWD for the later style trucks but I think I can just swap the pins over or splice wires. The heater blower motor is even the same, blue and blue/red.

Old style connectors: Heater blower resistor 4 pin, blower motor 2 pin.

New style harness in the center, demonstrating fitment. Old style plugs in my hand on the right

 

[bottombracket]

So why not just buy an old style underdash evaporator and old style heater blower motor? They are still available new. I’m sure I could make them fit.

The answer: the new style evaporator has a totally different expansion valve and fitment in the firewall is totally different.

3/2009 HZJ79

1/2022 VDJ79

 

[RHINO]

pretty cool to actually see the differences

 

[c2dfj45]

So why not just buy an old style underdash evaporator and old style heater blower motor? They are still available new. I’m sure I could make them fit.

The answer: the new style evaporator has a totally different expansion valve and fitment in the firewall is totally different.

3/2009 HZJ79

View attachment 3267683

1/2022 VDJ79

View attachment 3267684

We fit a Rav4 dash AC system to the 09 steel dash firewall......I don't recall anything too crazy about things not fitting. But that was a long time ago and I know for sure there has been some memory loss since then.

 

[sr5pickup]

For my conversion I used a Tundra harness, it had the same older style plugs you have showing. The tundra harness wires were the same count and also the same colors as the factory Hzj79 wiring, when referencing the ewd. I was able to locate the correct plugs and swapped them out repinned and everything worked without issue. Assuming your newer plugs look like these?

Next problem:

I realized that the blower motor and heater blower resistor plugs were also different post 1/2007. Fark.

I grabbed my 2018 HZJ79 wiring harness and plugged it in. As expected, it fits. I need to get my hands on an EWD for the later style trucks but I think I can just swap the pins over or splice wires. The heater blower motor is even the same, blue and blue/red.

Old style connectors: Heater blower resistor 4 pin, blower motor 2 pin.

View attachment 3267681

New style harness in the center, demonstrating fitment. Old style plugs in my hand on the right

View attachment 3267682

 

[bottombracket]

Care packages from @Japan4X4 arrived.

 

[Honger]

View attachment 3274841

Arguable the most important section of ducting... the "between the legs" vent. Why the heck did Toyota abandon this practice?

 

[bottombracket]

Also, look what I found in my parts stash: the correct firewall to dash mounting bracket that also holds the AC amplifier.

When installed, the AC bracket mounts between into the left of the glove box between the third heater duct and glove box.

A/C subharness clicks right into place. Satisfying.

 

[tucker74]

Arguable the most important section of ducting... the "between the legs" vent. Why the heck did Toyota abandon this practice?

When did they do this? My 100 series has it …

 

[Honger]

My Prado didn't have it... my 4Runner doesn't have it... think it ended in late 90's to early oughts.

 

[janyyc]

My Prado didn't have it... my 4Runner doesn't have it... think it ended in late 90's to early oughts.

My 2008 HZJ76 has it, but of course it’s the metal dash version

 

[bottombracket]

All right, let’s recap the last week.

Last Sunday, I made it home from Lone Star Land Cruiser Roundup, and it was like assembling the Avengers.

@orangefj45, Medium G, and Roark from Valley Hybrids had borrowed my 80 for the weekend, and had an afternoon and evening to kill until they flew out. @bkcruiser was here for the week. @AlbertoSD, @Spallet, @shanko, and @teleskier all stopped by.

While Georg and Roark tried to get my kei truck running, I swapped the HDJ100 for the HDJ79 oil pan. Important tech tip: if you want to measure how much oil goes into the 79 and 100 pounds, don’t forget to put the oil level sensor into the new pan… Oil gets very horizontal very quickly if you don’t.

After cleaning up the oil and the remnants of my pride, we were able to get the FTE and h152 combo all mounted up so that Bill could work on finishing the fab work on both trucks.

It was an awesome day.

 

[bottombracket]

Monday Bill turned his attention to the single cab motor mounts. We were eventually able to get the fan centered (ish) by slotting the frame to motor mounts and adjusting motor position. SCORE.

 

[bottombracket]

At this point, the single curb is now a rolling chassis. I need to wait for its engine to arrive, clean it up, and then it’s onto brake lines, fuel lines, and assemble the interior.

Steering column is next up.

 

[bottombracket]

Works sucked the last couple of weeks. I did finally attack the steering column surface rust.

The upper steering bracket had the ignition stuck in it, and I did not have the key, and none of the 50,000 spares I had fit. So I bought a new bracket and a full key set, part numbers above.

One of the three bolts holding the upper bracket to the main column is a yield bolt that shears off when torqued, and then is peened over for security. I ground it off with a die grinder to get everything apart. Thanks to @ATL Cruiser for knowing the real names of things.

I got it 80% of the way apart, and sprayed on some Rustoleum rust dissolver to see if it actually worked.

 

[bottombracket]

HOLY CRAP IT WORKS

Now my OCD is kicking in, so I’m going to go and take everything all the way apart, then dissolve the rest of the surface rust, then clearcoat the main bracket. I will then prime and paint the other metal brackets for the tilt mechanism. If I’m in this far, might as well go all the way.

I did put the key barrel into the upper ignition bracket, and that is satisfying.