How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Doug Your Own Question
Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8618
Experience:  Mitsubishi employed and Factory trained ASE certified technician
21364095
Type Your Mitsubishi Question Here...
Doug is online now
A new question is answered every 9 seconds

2003 eclipse spyder: driver side..passenger side..heater core

This answer was rated:

My mitsubishi 2003 eclipse spyder has poor heat output and very different on the two sides.The driver side is much worse than the passenger side.
Anthony replied that the problem is most likely in the heater core but could be the blend door in the dash.
Does the fact that the heat is so different on the two sides point to one solution over the oher?
Thanks
Rick
Chat Conversation Started
Doug C :

Hi,
This is most likely to be a problem with the core, either a clog or more likely a low coolant level inside the core.
The fact that the temperature varies between the two sides pushes more towards a level problem or possibly clog, rather than a blend door issue.
The design of the blend door is such that if it were to fail, it would simply moderate the temperature across all vents; it does not have side or per vent control .

Before doing anything else, I would recommend checking your coolant level in your recovery jug under the hood, and (when cold), checking the level in the radiator. Make sure both are filled.
In most circumstances when we encounter these vehicles having poor heat performance and variations, it is the result of small (not noticeable on the ground) coolant leaks from the engine-side of the radiator hoses. The aluminum corrodes, causing a slow leak that builds up green sediment, and eventually drips on the transmission. It is a long time before it leaks bad enough to hit the ground however, and at that point you are usually experiencing overheating issues as well. It only take a little bit for it to affect the heater core however.

Start with inspecting the coolant level. If it is low, add as necessary (may take several heat cycles and multiple engine revs each time). If it is not low, try warming he engine up fully, then inspecting the heat performance while the engine is at higher rpm (3k+) and see if your temperature variance changes any.
Next step would be to try back flushing the heater core as was mentioned before.

Customer :

There was a leak and my mechanic replaced the hose. the coolant level is ok.

Doug C :

Thanks. Was this when the heat started acting up, or has the heat been acting strange for a long time or...?

Customer :

This was when I noticed the heat problem but it was summer .

Customer :

I did notice some variability earlier when I would not have heat and then it would improve.

Doug C :

Thanks. I would still strongly suspect there is a low coolant level in the heater core at this point. It is relatively difficult to fill properly if you aren't familiar with the system.

Based on the variation of heat levels, that just further confirms that.

Doug C :

If you rev the engine high (while it is hot) and check heat performance, it should improve some as there is a higher volume of coolant being pushed through than normal due to the increased water pump rpm

Customer :

Do I need to go to a dealer or is there another way?

Customer :

I still ask WHY is it different on the driver and passenger sides?

Doug C :

No, it can be done yourself, it just takes a bit of patience to fill it. With no additional tools, just run the vehicle with the radiator cap off and the heater on full hot, and add as necessary. It will take several cycles to draw the fluid in.

The ideal way to do this is to use a radiator funnel, available at most auto parts stores. These funnels attach to the radiator and effectively raise the 'highest point' of fluid in the system, making the air bubbles find their way there quicker as opposed to being trapped in the core.....

Doug C :

The problem with varying temperatures is that the core is at an angle, and when there is air in the unit, essentially half (the lower half) of the core is hot and the upper (empty) half is not

Customer :

Thank you for your help. I will try your suggestions.

Doug C :

No problem. If you have any further issues, you can contact me on this page; there is no need to open an additional question I will continue to assist you if necessary














Doug and 2 other Mitsubishi Specialists are ready to help you