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Author Topic: Temp gauge dropping when heaters on  (Read 2652 times)

Offline R88TTD

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Temp gauge dropping when heaters on
« on: November 29, 2024, 12:29:34 pm »
Hi guys

I started experiencing new problems with MK5 gti
The temperature gauge drops from 90 to 75 then 50 gradually as soon as I turn my heaters on

Now the heaters are blowing hot air as normal
I asked about and some tell me the battery , some tell me the temp sensor and some are telling me the thermostat, water pump was changed about 15k miles ago so that ruled out

No head gasket issues , no over heating

Just wondering if anyone had this issue before Thanks

Offline ZoliWorks

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Re: Temp gauge dropping when heaters on
« Reply #1 on: November 29, 2024, 03:55:04 pm »
If you want to find out if it's the thermostat or not, go on the highway, drive at a constant 130-140kph without the heater and see if the temp drops. If it does, it's the thermostat.
Mk5 Jetta 2.0 TFSI BWA | Manual | Mk6 GTI Front | BorgWarner K04 Turbo | Sachs X-Tend OEM+ Clutch Kit | Ta-Technix Air Intake | Ta-Technix 200 Cell Downpipe | Ta-Technix Intercooler | Stock Injectors | Vis Motorsport 175 bar HPFP | 300hp


Offline Octoparrot

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Re: Temp gauge dropping when heaters on
« Reply #2 on: November 29, 2024, 04:39:27 pm »
I'd put my money on the thermostat.

Offline mjmallia

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Re: Temp gauge dropping when heaters on
« Reply #3 on: November 29, 2024, 06:18:03 pm »
Thermostat for sure
Mike

South Coast

S3 8L ---- Golf Mk4 GT TDI ---- Lupo GTI ----  A4 B6 Sline ---- Golf Mk5 GTI