latched on/off output

howie ll wrote: How can you run the AC if the engine is off? The compressor needs the engine running. A latching relay buy the way is what the vehicle manufacturer would use.

I do not want to run it with the engine off, sorry if I gave that impression.

howie ll wrote: He wants one touch, I was thinking of items which use one momentary button such as rear defog, that requires a latcher or at least a solid state latching circuit. This all sounds like a bit of Heath Robinson, = a Kludge to me. Why not just buy a retro kit, there are still manufacturers in the, US, South Africa and Israel. Heck up to 7-8 years aqo when we were still installing them we used an English supplier. In the US try ARA. Note unless going into a Japanese Vehicle which has ready prepared wiring, compressor mount etc. this is a 3-4 day job for an EXPERT who is that rare beast, a good mech. and a good sparks. Under engine block, drop either alternator or power steering compressor, mount AC bracket or change existing. Fit new drive belt. Drill 2-3" holes (2) in bulkhead, drop AC h/exchanger in front of rad, dashboard out, loads of wiring etc. etc. etc. And don't forget back in the day we could pull an E36 dashboard in about 20 minutes, i.e. strip from floor to windscreen. We stopped that part in about 98, after that everything in the UK got air ex factory.

I never thought about a rear defroster but that might serve the purpose. I already have the system installed, all I need to do is wire it and charge it. It was a PITA and do not plan to do this again.

oldspark wrote: I missed the single button.... In that case... ... where the circuit is powered by IGN +12V. And the output controls the relay. I suspect it powers up in the on state (+12V out), hence connect that to a relay connected to IGN +12V... Or any flip-flip or divide-by-2 circuit (eg, the CD4017 can be div-2 to div-10 etc). Or an on-off switch - push-button or rotary...

I am trying to look up the symbols on this diagram, I do not really understand diagrams like that (wish I did).

X 2 with that comment, I never got involved with the heavy stuff, I just did the wiring. Push button switch to say timer relay, ignition controlled, timer relay shuts after about 10 minutes. If its a latching relay you can use a momentary push-push operation.

howie ll wrote: X 2 with that comment, I never got involved with the heavy stuff, I just did the wiring. Push button switch to say timer relay, ignition controlled, timer relay shuts after about 10 minutes. If its a latching relay you can use a momentary push-push operation.

So I would have to turn the system back on every 10 min?

That time was an example but you should never need more than 10-15 minutes, especially not with AC. I had a couple of Maximas in the mid 90s where the defogger switched off ex factory after 10 minutes.

howie ll wrote: That time was an example but you should never need more than 10-15 minutes, especially not with AC. I had a couple of Maximas in the mid 90s where the defogger switched off ex factory after 10 minutes.

Sometimes during the summer I would want on for long periods of time.

I think we're at cross purposes, I'm talking about a an electrically heated rear and or front window, you're talking about AC. No timer needed for the AC of course.

Those symbols in my last diagrams are inverters hat exist as integrated circuits (ICs). There are hex inverters - 14-pin ICs with 6 inverters & 2 pins for power (which are not shown on the diagram) - such as the CD4049, but there are others as well as many way of making inverters (using other logic chips such as NAND and NOR gates, or transistor, etc). The other symbols are resistors & a capacitor.    Using electronics or chips (ICs) there are many ways to do what you want. But that will involve soldering etc which is not liked by many.