No cooling fan operation when temp light red on .

[cherrybomb]

The 2003 Beetle TDI H/B (Mfg. 3/03) will activate the flashing RED light when prolonged Idling W/O a/c on in 50 degree weather. Both cooling fans. work well and run either Hi or Lo speed with A/C (cooling and R134 good) )in hot weather. Have replaced the thermostat,, temp sensor in flange (Green), both 50A strip and 30 A green fuse on top of battery and the Radiator Thermal Switch.. Have read multiple threads plus Andybees and Oilhammer tips regarding the various tests on overheat and fan testing. We tested the Rad Therm. Sw. by jumping the red to other 2 wires and fans ran as suspected. 1. Will the red wire at Rad Therm. Sw be hot when ign. on ? 2.Where is it powered from, the FCM?' Found it strange the A/C and fans work well ; then when on manual air flow and heat, the fans do not operate when the light is flashing red. The mgf. date and changes from 5/03 confuse us also. We only have the Basic Free program from Ross Tech.

 

[Zak99b5]

Isn’t light flashing the low coolant alert?

 

[cherrybomb]

Initially we thought that also. Filled the coolant jug to MAX then drove for a few weeks keeping check on level. The coolant level is same now and the flashing light came on again after extended idling again. We checked many items that are good, but stumped on the cause of the problem. According to the ECM thru the ADLC the Temp runs 192 when driving and holds steady.

 

[Zak99b5]

The sensing prongs in the coolant bubble can go bad and trigger false alarms. You could try to clean them, or just get a whole new ball.

 

[cherrybomb]

Question? Does coolant level drop when engine reaches operating temp? Otherwise we also have new jug and filled it to Max line level. With A/C going, both fans run at low or high if needed. No idea if they are powered thru the FCM or off the fuse or perhaps a relay? Parts Cat. indicate a change after 5/03 in wiring. Ours is 3/03.

 

[cherrybomb]

Question? Are cooling fans powered thru the FCM when only blower sw. & Ignition on? Yes No
? Where does the Fans 12V originate (fuse)when no no A/C & only KOEO ?
? With March 2003 Mgf (Not date May 03), will the #53 be a Fan Relay We have 1 Yes No
? On the Rad. Thermal Sw, the Red (#2) has 12V with A/C on, but if only int. blower
and no A/C., is there 12V on #2? -- Yes No -- Due to the Mgf. Date, wiring confusion?