Popular Motoring - Technical: Fiesta Thermostat Conversion
"Thermo conversion"
October 1981



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Technical: Fiesta Thermostat Conversion

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Popular Motoring - Technical: Fiesta Thermostat Conversion - Page 1

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WORKSHOP: ENGINE - Thermo conversion

With car makers cutting costs wherever possible, some models are becoming extremely basic - both inside and under the bonnet. Here, Martyn Williams comes to the aid of Ford owners without a thermo fan control.

ALL CARS ARE TOO DEAR, but in an attempt to make budget models as competitively low priced as possible, car makers have been leaving out many of the little extras we usually take for granted. These include courtesy lights, heated rear screens, cloth seats, even carpets in some cases.

On the small engined basic Fiestas and some early model new Escorts, Ford have managed a miserly bit of cost-cutting by omitting a thermostatic switch in the electric radiator fan circuit.

Some owners though, complained that they didn't like the fan constantly whirring away, especially in the depths of winter.

Ford responded by producing a thermostat control conversion kit for Fiestas under part number A78SX8570AA. Costing just £8.71, it contains all the necessary parts and is fairly easy to fit.

At present, there's no official kit for the new Escort but a dealer could supply the thermostatic switch and all the other parts. The extra wires and plugs could be easily installed by following the Fiesta diagram right.

The wiring can be checked when completed by connecting a test bulb to the plug which goes to the fan motor. Short the two wires to the thermo switch together and the lamp should light.

Ford suggest that the connectors should be coated with grease before joining them up.

Make sure the new fan switch wiring is securely fitted under the clips holding the original loom.


Car: Fiesta (and New Escort - see text).
Problem: Cooling fan runs constantly when the ignition is switched on (950 Pop and 'L' models plus most 1.1 Escort built before June 1981).
Cure: Fiesta-fit conversion kit. Escort - see text.
Parts and prices: Fiesta kit £8.71 inc. VAT.
Tools required: Drain tin (coolant), 13mm spanner, screwdriver, torque wrench and socket to suit thermostat (29mm). You'llneed a fairly deep socket to clear the switch top, we used an old Whitworth socket.
Average time: Half an hour.

1. This is the Ford kit. Only extras you'll need are some grease for the terminals and some gasket cement for new housing.

2. Disconnect bottom hose and drain coolant into a suitable bowl. The top hose can then be removed.

3. Coat faces with gasket cement and fit new housing. Note the fibre washer which goes under thermostatic switch.

4. It's easy to forget earth lead which goes to the housing bolt on earlier models. Thermo switch should be torqued to 20lb-ft.

5. Disconnect existing plug from fan and thread it down to new loom plug which is routed under radiator.

6. Here the original plug has been fined to new loom. New lead, complete with plug, goes to fan motor.

Captions -

Middle - Diagram shows route of the new loom under the radiator. It should be neatly clipped alongside existing wiring under the bonnet.