No warm air flow

Step 1: Warm air duct

Check warm air duct from heater to body for tightness

Possible defect


Clamps loose or hoses dropped down or damaged

Secure loose parts, replace damaged parts with new ones

Step 2: Fuel delivery

Loosen hose clamp, disconnect hose to heater briefly (2 secs) at fuel pump, then check whether fuel is delivered by pump. Catch escaping fuel in a cloth.

Possible defect


Check fuel supply

Fill fuel tank

Fuel filter blocked

Install new fuel filter

Strainer dirty

Clean strainer

Fuel check valve blocked

Replace fuel check valve and readjust delivery capacity

Step 3: Glow-spark plug

Switch heater off. Remove glow-spark plug and check

Possible defect


Thermo switch defective (no current, glow time too short)

Install new thermo switch

Glow element open

Install new glow-spark plug

Glow-spark plug dirty

Clean glow-spark plug

Ignition contact breaker defective or maladjusted

Adjust contact breaker or replace if necessary

Ignition cable or coil defective

Test ignition system and install new parts if necessary