1993 ford escort 1.9lt cooling prob

old broad and old cars make for an ugly mix. and here we have both!!
this is a summary of the problem. the cooling fan works upon start up. however when it shuts of it does not come back on. i bought a relay but can't find where it goes.
things i have done already:

new thremostate
new heat sensor
new compt chip.
disconected heater cause i was loosing coolant mid way under the car, they said heater was bad :banghead:

help help help

Is the car overheating? The fan isn't supposed to run constantly. The only time they'll run the fan is if they sit idling for a long period of time or are in very slow traffic on a hot day. Overheating without either of those conditions indicates a coolant system problem. ie: Water pump failure, radiator hose(s) collapsed internally, system blockage. Was the system drained and flushed and the hoses and coolant replaced when the new thermostat was installed? It should have been. If not then have it done.

It does sound as if your heater core has sprung a leak. You need to be more specific when you say you "disconnected" it, though. Did you disconnect the coolant hoses from it? You have two alternatives, but only one that I'd persue: You can reconnect the heater hoses and have a leak stopping additive added to the coolant and hope that it will plug (and keep plugged) the leak point. Or you can have the heater core replaced. The latter is your best bet.

What's a "compt chip" and where in the fan/cooling system is it located?