Thread: Looking for Air con thermo amp / evaporator

Thermoamp? What's a thermoamp? Do you mean thermostat? They usually have a capillary tube stuck into the evaporator core in between the fins, or possibly down stream in the air duct.

Look Here:
Aircon electrics
I have attached a picture so you know what you are looking for.
It should have been under you passenger seat at the back.
Relay then thermo amp with about 8 wires coming out and then fuses then relay. I daresay they would have kept this combo together, maybe on the firewall next to the heater box? or have a peek under the removable air top vent patch thingies on the mudgaurd... I have my light upgrade relays there...
Let us know when you find it...

The Thermoamp is what they call the black box unit. Essentially the thermostat.
I know this is a dumb question but where is the evaporator? Is it behind the
fan motor?

I thought the capillary would measure air in the duct rather than temp at the
evaporator?

Originally Posted by fender22

The Thermoamp is what they call the black box unit. Essentially the thermostat.
I know this is a dumb question but where is the evaporator? Is it behind the
fan motor? Yes

I thought the capillary would measure air in the duct rather than temp at the
evaporator?

What's wrong with your AC?

Without knowing your exact layout, the evaporator has the refrigerant pipes connected to it. It will be downstream of the fan, ie the fan blows through it. It is generally rectangular and covered in aluminium fins inside and has a drain pipe to the outside of the car for condensation. Can't be that hard to find.

Originally Posted by fender22

I know this is a dumb question but where is the evaporator? Is it behind the
fan motor?

It's under the dash on the passenger side in a black plastic housing. To get to mine I evacuated the aircon gas, disconnected the piping and removed the under dash unit. Not the easiest thing to get to otherwise.

See here TDI Defender Air conditioning Fixed

On the first photo you will see a white plastic electrical connector on the top LHS of the evaporator. I recall that was to the thermostat (hidden from camera view) which ran on the outside of the evap.

The second photo shows the evaporator and fan housing (apart)

Whats wrong....ok
Driving me nucking futs! Bought one from the wreckers about 4 months ago out of a similar era Defender. The guys that put it in where total aholes. Whinged the whole time during what turned out to be a fairly simple installation. When working properly it's freezing cold and cycles on and off perfectly. Gas pressure tests perfect and have bridged pressure switch out and still cuts out.

Problem is it cuts out after being on for 10 or 15 minutes, then may stay off for 5 or ten minutes. When it cuts out, fan stays on but the control circuit goes dead Ie can't hear relay clicking cycling when I turn the knob and compressor drops out. No rhyme or reason to it either. Usually cuts out after it's been on for say 10 minutes and might go off for 5 or 10 minutes then come on again. Sometimes it's not even going when I first start the car, then comes on after 5 or 10 minutes. Have had periods of three or four days where it seems to work perfectly, then back to the same again. Seems to be getting worse too, can hear relay chattering when it tries to pull in again. Definitely ruled out the compressor and pressure switch as ok. It's in the control circuit somewhere for sure. Either a dodgey thermoamp / contacts or a hot joint somewhere. Could be the 4 pos fan / thermostat switch possibly too but I doubt it. I think power goes to the switch and then out to thermo amp then compressor. Normally when working you can hear the thermo amp / relay audibly clicking in and out cycling as it should. If I can find the thermoamp I'll just buy another one and replace it and it will either fix it or I can eliminate it and move on.

There is a main power relay in the battery box under the pass seat and another power type relay behind the air con. Both of these have been replaced. Haven't been able to find the thermo amp to date but have a better idea
after seeing your photos there. Is a bit more agricultural looking than I thought so may have missed it. It's not under the pass seat and doesn't seem to be behind the aircon fan unit.

You still having issues?

I have a TD5 Non thermo amp system never been installed with all pipes and hoses, compressor, condensor, rec/dryer. will solve all your probs.