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sassankh

Member

From: Sweden

Registered: 2025-02-07

Posts: 2

Heater Cold & Temperature Drops While Driving

I have a 2010 Peugeot RCZ Petrol, and I’m having an issue with the engine temperature dropping while driving and the heater blowing cold air.

Here’s what I’ve checked/replaced so far:

✅ New thermostat (Checked with a computer, and it opens correctly when hot)

✅ New water pump

✅ No air in the system (Properly bled)

Both hose are warm and circulation of the water show in the water tank

I also noticed that one of the hoses going to the cabin radiator is hot, while the other is cold.

Any ideas on what could be causing this? Could it be a clogged heater core, a failing temp sensor, or something else? Would appreciate any advice! I am really cold in here Sweden -10

Thanks in advance! ??

OAT

Member

From: Borders/Dales

Registered: 2017-01-03

Posts: 1,013

Re: Heater Cold & Temperature Drops While Driving

Being a van forum I doubt we have anyone with actual experience on an RCZ. 
Nice looking car though.

But being a general heater problem, I suppose we can all have a go. 

When you say "one of the hoses going to the cabin radiator is hot, while the other is cold", do you mean realy cold or just not as hot as the other? 

Have you confirmed flow at the "cold" hose?

Any thermostat control for cab temp or aircon fitted?

The fact that it works fine then fails suggests all major components are basicaly ok.  If you are getting good temps, circulation and pressure I would be thinking electronics and/or sensors.  But not being very familiar with modern electronics wouldn't know where to look.

Is there anything consistant when it fails, like after certain time or at certain temp?

Last edited by OAT (2025-02-07 20:47:30)

kenbw2

Administrator

From: Preston

Registered: 2017-11-26

Posts: 1,614

Re: Heater Cold & Temperature Drops While Driving

I have a 2010 Peugeot RCZ Petrol

I was gonna say, this is a strange model of DispatchExpertScudo 

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2000 Citroen Dispatch 1.9TD XUD9 Camper Conversion
1999 Citroen Dispatch 1.9D DW8 Disassembled Camper Conversion
1996 Peugeot 806 1.9TD XUD9 Spare vehicle
1998 Citroen Synergie 1.9TD XUD9 Snapped timing belt

sassankh

Member

From: Sweden

Registered: 2025-02-07

Posts: 2

Re: Heater Cold & Temperature Drops While Driving

Hi Admin,

Haha , yeah, I know this isn’t exactly a Dispatch/Expert/Scudo, but I’ve asked in every relevant forum and didn’t get a solid answer, so I thought I’d give it a shot here. Sorry for bringing it up in the wrong place!

Regarding the issue:
Thanks for your time OAT, When the car gets warm, the exit hose is warm, but the inlet hose stays at a normal temperature. I remember once when my friend ran a diagnostic, he asked me why the system was showing an inside temperature of over 1000 degrees. I’ve checked all car details but couldn’t find any in-cabin sensor. I thought maybe that reading was just a default when no sensor is available.

I know you guys are experts in VANs, but experience is always more valuable than just theory. When you mentioned that sensors could be the issue, it reminded me of this strange diagnostic reading.

Any ideas on what might be causing this?

Thanks in advance!

OAT

Member

From: Borders/Dales

Registered: 2017-01-03

Posts: 1,013

Re: Heater Cold & Temperature Drops While Driving

We do have a couple of members quite proficient with heating systems on our vans but mostly with far more primitive systems than I suspect yours might be.

Hopefully they might have some suggestions though.

RegW

Member

From: Bristol

Registered: 2024-04-21

Posts: 350

Re: Heater Cold & Temperature Drops While Driving

Do RCZ owners get pissed of when folk like me say "Hmm, looks an Audi TT dont it?" 

Anyway as I got proficiency badge in the cubs, I'd say the heater core is blocked or there is an airlock
air bleeding/checking would be the first thing to check of course
Next be sure you have the heater inlet and outlet correctly identified
the heater core is usually supplied from the engine within the thermostat zone so it can circulate coolant
through the heater whether the thermostat is open or shut for faster warm up.
the outlet on my van runs to the header tank so pre thermostat.

When my core was blocked, the supply hose would get hot but the outlet back to the header cool or warmish at best.
I found using Rad flush and back flushing was partially helpful, but it was only when I fitted a new core that it got proper toasty.
Your RCZ being a 2010 car suggests its quite feasible for it to have accumulated a build up of crap in the last 15 years.

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When all else fails, RTFM  - 2006 Expert 2.0 HDI/110