Truck #2


I have this other circuit design that looks like it could be modified
and adapted to actually giving real temperature control to the USE heaters.
Since the heater element runs on pack voltage this would be a high voltage
control with a pot on the dash that changes the temperature. The pot
would be opto isolated for safety. It would be just a single board
that connects after the heater relay to pack voltage, and uses high
voltage fets for controlling the power to the heater element.
Depending on the space available, it could mount in the heater box
itself.

Interestingly the pressure sensor was not wired in even though it was
in the factory schematic. It’s easy to see where is could be added
into the circuit, but clearly had never been wired in when the AC was
installed. You almost cannot see the pressure sensor. It is wired in
right under the Dolphin and on top of the AC compressor. No mating
connector in sight. It was so hard to reach I could not test it’s
continuity with my meter. The spare compressor I have shows infinite
resistance at no pressure. So I am assuming that my charged system
would show close to zero ohms. This means the compressor could be run
without pressure, at least on this truck.

Slick system. As the temperature knob is rotated warmer, the
compressor slows down. It pulls around 5 amps from the pack at max
output in about 75 degree air. So it’s not well loaded for a max amp
test. That will have to wait until summer.

This truck is becoming a keeper.

Yes!!!!! The air conditioning is fixed!!! What a bunch of work that was!! The story goes like this. The factory had a learning curve as they built their first few vehicles. The #2 truck was an early version. So the wiring for the AC and heater had been set up in a way that was very untested. Instead of a switch to turn on two relays, they used one of the pots that is part of the temperature control on the dash. As the pot is rotated, it slowly brings the voltage up to the coils of the two relays. The problem is that the relays don’t come on at the same time!! So the heating element would turn on long before the water pump would and smoke the heating element. That’s why this truck never had a functional heater. The air conditioning had a bad crimp at the AC controller plus the ground for the AC controller was corroded badly. I had to clean the pins and sockets up for each of the 12 connections. That’s all it took!

I also added the lighted dash switch that most trucks have to turn on the heater. Now the AC and the heater can be run completely independent of each other, or at the same time. Nice!!

The wiring to the AC compressor and controller can reach the top of the Dolphin. This will allow me to test my spare AC parts.

What really made this debug work well, was spending a week making a schematic from crummy notes that had been faxed from the factory 12 years ago. It was a lot of work. But it made the debug of the AC system far better. Now I have a massive 18″ x 24″ drawing of the entire AC and heating system. This never existed before! I’d like to add AC to the #1 truck now that I have a schematic, parts, and wiring.

The only odd item left to repair is the heater/AC blower. It’s always on. Even when the selector knob is off, the blower runs. It’s speed can even be adjusted from the fan switch. I didn’t see any rigged wiring. But I suspect the wiring was modified somewhere and it needs to get fixed.

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