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Heater Only Blowing Hot?

Fast Bug

Well-known member
Joined
1 Nov 2017
Messages
230
I've an annoying problem where my car only seems to like blowing hot air no matter what the temp is set at unless it's on the coldest setting. Any ideas?
 
This happens a lot with VW T5's

It could be a resistor.


Wait for Demort to get online :mechanic:

:thumb:
 
I'd suspect it is a sensor fault. The one that reads the internal cabin temperature. If it's a gen 1 car I believe there is a way you can get the climate control to display the internal temperature. You will know it's that as the reading will be wrong.
 
Yes it's a gen 1 car (1999). I'll have a google and see what to check thank you!
 
When I had a very similar problem I sourced a second hand sensor that sits under the passenger air vent in the cabin. Sorted it out.
 
Tom and Toml have alreay said what i think ..

The interior sensor is probably under reading so if it thinks the cars temp inside is -5 then every setting other than Low will just blow hot air.

If it reads that low as well which it may well do then your A/C also wont work .

Depending on the year then the sensor is either in the center panel or behind the round vent/ dash trim in the dash on the n/s .

It can only be proved though by looking at actual values for the heater system with a tester .
 
By the looks of the cost of them I might just buy one and pop it in for peace of mind. It's booked in for an MOT at the end of the month and an a/c regas. I've got bills for new condensers but not refilling the system :dont know:

Appreciate your help fellas :thumb:
 
I cant belive any garage would replace the condensors and NOT refill the system , i would guess thats its just not been mentioned but incorperated into the bill .

This sensor CAN stop the A/C from working .

Please let us know if it was just the sensor though .. it helps people when searching in the future :thumb:
 
I'm hoping it fixes the a/c as well. I've ordered the part and it should be in on Tuesday. I'll have a look at the weekend and see where the sensor is
 
Pop out the round vent on the passenger side first and see if its there .

You can pull it out with your finger nails and the sensor should be behind it .
 

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If it is a gen 1 then you should be able to access the 'hidden' menu. Mine it a gen 2 so I have never been able to test this but I remember reading about it a few years ago.

A quick google and I have found this;

Press and hold the UP button then at the same time press and hold the RECIRC button in.

After 5 seconds or so of holding the buttons in the display changes to 1C.

Let go of the buttons.

To see the reading corresponding to 1C press the button on the climate control below the UP button
(this is the button for directing air through the centre dash vents).

Also this;

0c - ERL
1c - Oil Temp
2c - Inside Temp - From the Sensor mounted in the Aspirator Assembly at the side of the Dash
3c - Outside Temp - From the Sensor inside the Air Inlet of the A/C Unit
4c - Outside Temp - From the Sensor in Front Grill of the Radiator. Data is fed to the Climatronic from the Instrument Cluster. When not moving, the Instrument Cluster OBC Temp Display retains it's last setting until moving. This is to prevent heat emanating from the Radiator affecting the Temp Sensor. The Climatronic uses the lower of the two values in determining Fresh-Air Temp.
5c - Outside Temp - matches OBC outside temp display
6c - Coolant Temp
7c - Footwell Discharge Temp
8c - Sun Sensor (dash top)
9c - Sun Sensor
10c- Passenger Compartment Fan Speed
11c- Passenger Compartment Fan Voltage
12c- Temperature Mix Flap Command (1=COLD, 100= HOT)
13c- Temperature Mix Flap Position
14c - Central Flap Command
15c - Central Flap Position
16c - Footwell/Defrost Flap Command
17c - Footwell/Defrost Flap Position
18c - Recirculation Valve Command (1=OFF, 100=RECIRC)
19c - Recirculation Valve Position (feedback)
20c - Vehicle Speed in kph, updates once per second. This is True Speed, not the Speed+Safety Margin displayed by the Speedometer.
21c - Engine RPM in hundreds, also updates once per second
22c - ?
23c - ?
24c - Sun Sensor, Exterior Lights Switch, and Panel Lights control (term.
58 & 58d voltage) - used for A/C Panel Display Illumination
25c - ?
26c - ?
27c - ?
28c - Fan Speed
29c - ?
30c - Engine Run Time in seconds (255max.) (=0Xff)
31c - Timing Counter
32c - Displays Test
33c - Software Version (usually 3.4)
34c - ?
35c - Outside Temp from Inlet Sensor (filtered)
36c - Temp

I'm not sure how accurate this is but it would be nice to know if t works
 
Funnily enough I've had this exact problem today. I take it the sensors quite cheap, is it an easy/quick diy?
 
I'll have a play tomorrow when I get the car out of the garage to give it a clean. The sensor was just shy of £25 + VAT from Portsmouth OPC and should be in on Tuesday
 
The round cover popped off really easily, the sensor is indeed behind it and covered in fluff and dust which probably doesn't help so will replsce it as a matter of course.

Now with the a/c menu, I get 0c - ERL. What the heck is that? If I google it, all I get are links that show the list of codes but not what ERL means. Any ideas?
 

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