Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1979 Ford FiestaFACTORY OEM SERVICE PROCEDURE
Thermal Vacuum Switch (TVS)
- Remove TVS from air cleaner. Attach small, center nipple to a 24 x 1/4" piece of vacuum tubing which is connected to an external vacuum source. Leave other nipple unattached.
- Obtain a can of R-12 refrigerant, a safety valve and a suitable piece of refrigerant hose. With safety valve closed, attach R-12 can to valve and hose to valve.CAUTION: Wear eye protection and make sure area is well-ventilated. When working with R-12, make sure engine Is NOT running.
- Invert R-12 refrigerant can, slowly open can valve, and apply liquid refrigerant to TVS to cool it to 40°F (4°C) or less. Apply 16 in. Hg with external vacuum source and hold. Vacuum level must remain at 10-16 in. Hg for 60 seconds. If not, replace TVS.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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