Pirate Jenny gets some new bits.

[bobclevenger]

It's aluminium. I have corrected the earlier post.

[CrAzYMoPaRGuY]

It's aluminium. I have corrected the earlier post.

I see that pulley and I think "Wow, cool pulley"!
LOL
I've never seen that pulley before, and I've seen lots of pulleys. If it's Jensen specific is it "SP" specific I wonder..?

[Steve Payne]

Crazy

It is an SP pulley, it is a smaller diameter so it makes the pump turn faster and it is supposed to pump more water.

It will only fit the H series engines as the belts are in a differant place to J series 440's.

I was told they were a Mopar part. They are aluminium and are often the cause of belt slippage due to the fact they are worn out.

Steve

[bobclevenger]

Time for an update.

The A/C is finished and is working fine. A local shop had some new hoses made up to fit; the hose makers said that the other hose was in better condition than the new ones they could make ; they installed some adapters to make everything connect up correctly. The shop then charged the system up with R-134a and gave me the bill. I've felt colder A/C systems, but I didn't like them. This system is very nice as far as I am concerned. It's a car, not a meat locker!

Someone here on the Forum asked me why I didn't connect the cooling fans so as to be wired in series and thusly run at half-speed when maximun cooling is not required, and then to switch to parallel connexion when max cooling is needed. I basically said that "this works" and that I didn't know how to do that. Well, that little idea kept nagging me, as I thought it was a pretty good one. So I sat down and designed a relay circuit that does exactly that. Preliminary tests look pretty good; both fans come on at low speed when the ignition is switched on, and they both operate at full-speed when the otter switch earths. How half-speed works as to cooling the engine remains to be seen. It ought to have better air flow than one fan at full-speed and one completely off, which is what it has been doing whenever the otter switch is not earthed.

I think I shall go back to a belt-driven water pump because that will allow me to run two belts over the A/C pulley (it has two grooves and I'm only using one now). For now the electric water pump will stay in service.

After final wiring and testing, I shall post the series/parallel fan circuit here.

[bobclevenger]

OK, the new fan circuit works. At tick-over with the car stationary the slow speed is almost enough cooling by itself; high-speed only switches on for brief periods of time. This is without A/C being on. When the high-speed mode is engaged the temperature comes down right quickly. Relay K3 switches the fans to high-speed whenever the A/C compressor is running.

An added feature if it is important to anyone is that two fans at half-speed are quieter than one fan at full-speed.

Here is the basic circuit:

Relays K2 and K3 are common automotive relays.
Relay K1 is a DPDT relay with a 12 volt DC coil and contacts rated at 25 amps. It is NTE Electronics part # R55-11020-12F. The contacts on this relay are not numbered, so one must look ar the contact arrangement. One could use two SPDT relays in parallel, but that would take up precious space.
The circuit breakers are marked as 20 amp, but it remains to be seen if that is enough capacity.
This circuit was OK all along.

Below is the circuit for the electric water pump version:

The comments for the basic version apply to this one.
K4 is a common automotive relay used to control the electric water pump.
D1 is a non-critical diode that stops K4 from backfeeding through K1 and the fan motors when the ignition is off.

With this wiring, the water pump runs whenever the ignition power is on. It stays running as long as the otter switch is earthed, even after ignition power is shut off. This removes residual heat after shutting off the engine ("heat soak"). This works better than having the fans run, due to the location of the otter switch; it is in the coolest part of the system. The fans, were they to run after shut-off, would quickly cool off the water nearest the otter switch causing it to un-earth too soon.
This circuit had a bug, but it has been fixed.

[Wallace]

I was just working my way through that one when you posted the red message! I can see in the second drawing the water pump is permanently wired, what is the A/C clutch operated by, is it the A/C cut in switch?

Mike

[bobclevenger]

I was just working my way through that one when you posted the red message! I can see in the second drawing the water pump is permanently wired, what is the A/C clutch operated by, is it the A/C cut in switch?

Mike

The bug was that the water pump was always on; it worked really well to drain a battery!

The A/C clutch is wired from the factory. It turns on and off as the A/C is called for. I just spliced the relay K3's coil to the wire that goes to the A/C clutch so that K3 will pull in any time that the A/C compressor is running.
Probably a bit of "Belt and Braces" since the cut-in switch ought to accomplish the same function. I just don't trust pressure switches.

[Wallace]

I think what was throwing me initially is the relay schematics not showing the contacts in their rest states, ie pin 30 to 87a etc., but I understand it now.

Mike

[bobclevenger]

Yes! That bothers the He11 out of me, but it's the only relay symbol my drafting programme has.

By the by, if anyone is wondering about the wire for the heated backlight, I connected it directly to the ignition power line (normally open contact of K2) so that it is powered any time the ignition is on. I have plenty of current capacity and rarely switch it on anyway.