It seems the thermistor is a thorn in the side of many Fit owners (including myself). Unfortunately, however, I can't seem to find any recommendations or assistance on how to replace it. Any experience out there?

 

1. Drain the engine coolant (see page 10-7).
2. Remove the thermostat cover (A), then remove the
thermostat (B).
3. Install the new rubber seal (C) onto the thermostat,
then install the thermostat with the pin (D) up, and
install the thermostat cover.
4. Refill the radiator with engine coolant, then bleed the
air from the cooling system (see step 8 on page 10-

 

Thermistor, not thermostat. He's looking for the A/C thermistor I think.

It's embedded in the evaporator. Access requires evacuating the refrigerant and removal of the evaporator.

But replacing it will not alter its characteristics. It's working as designed.

Polaski did a DIY on adding a resistor to alter its function. Here's the thread on it. This is for a GD but the principle should be the same.

If you really want to get at the thermistor I can post the shop manual pages on it.

 

Thanks for clarifying.

 

Steve244,

You're right on the money...the A/C thermistor is what I was talking about.

I live down in sunny (read: scorching) south Florida and I'm having the issue of my evaporator coil freezing on long trips (~>1hr) with the A/C on. Through my browsing of this site, it seems the thermistor is usually to blame. Thoughts?

 

Recirc or fresh? Try the opposite.

 

I suspect you're right. Usually the complaint is that it doesn't get cold enough as the thermistor cycles the compressor too frequently (by design). The opposite condition could be caused by not cycling enough (and this isn't by design).

If it's out of warranty, replacing the thermistor is probably about a $400 repair even though the part is $15.

It could also be caused by low refrigerant. I'd have it checked.

 

malroux,

Every time I've had the issue, it's been recirc. I'm going to try fresh on my next trip to Key West...

-break-

Steve,

I took it in twice for the same issue while under warranty...no dice (I'm kicking myself in the butt for not pushing the issue). Now, out of warranty, I finally dug into these forums and found out it is likely the thermistor. I'd rather sweat profusely then dish out 4 bills . I'll monitor it using fresh air.

As an aside...especially with fresh...this A/C definitely does suck. Only thing that pisses me off about this car.

 

If I lived in a hot sunny location like florida, I'd definitely look into a good heat rejecting tint job. Well truthfully if I lived in fl I'd look into how to move somewhere else, but you get the point.

 

I had my windows tinted...it helped, but the Florida sun still overpowers.

Working on it. It's a freakin' banana republic down here. The sun is the least of it. Good customer service, live music, microbrews....never to be found.

 

Great comment and assistance. I think the a/c temp sensor (thermistor) is what he's looking for, too. If he doesn't I can also. How do you know the thedrmistor is working as designed?. Is there a junction where resistance can be measured?

 

If it's not as cold as you'd like (frequent compressor cycling) I think it's working as designed. The thing is weighted on the side of economy rather than cooling.

If the evaporator is icing up something is wrong. Might be the temp sensor. The shop manual describes a test where you pull the sensor, put it in cold, then hot water, and measure the resistance against a table they provide. The problem is to remove the sensor you'd have to purge the system and pull the evaporator (after yanking the blower housing). There's no practical test of the sensor short of this.

 

Before going to the trouble of pulling the unit and loss of refrigerant if you can find the junction of wiring, separate and measure the resisdtance when you pour cold water on the evap and then hot water Its not a test of accuracy but whether the thermistgedr is reactuing to temperature change. If it is then measure the ac air output temperature and check against the shop manual data.
Are you putting your air on recirculation and in max fan? And make sure your drain functioning properly at full drainage flow. Back up the condensate drain and your a/c capacity drops off considerably.

 

Every time the icing occurred it was on recirc and, I think, max fan. I will try fresh air next time. Where would I check the condensate drain?

 

while getting coffee my a/c guy said that you may have too much coolant; did you have it filled recently and especially did you convert from R12 to R134a? If the later the recharge should only be 3/4 of the R12 recharge capacity. In his opinion overfilling is more than half thev reason for icing. He doubts the thermister is at fault.
good luck

 

Don't tough the thermistor... The system is low on charge. This is exactly what they do when they run low.

Dont do anything else until you check the charge.

 

I am certain they are all R134. The fit came over here, what in '07, and all the cars in '95 were switched over to R134.

You can overfill them... However, if he didn't touch it, refrigerant doesn't leak into the system, it leaks out.

You are correct about the thermistor... I chased my tail with this on a 97 stratus... turns out when it is just on the verge of being low, it acts exactly like he has described. I now have my own gage set and a 30lb bottle of R134. I just top it off and go with it.

 

Thanks...will check charge and report back.

 

I checked the charge (r134a by the way) and...sure enough...it was low. I filled it to about 45psi (as recommended). The air seems cooler. We'll see if the icing occurs on the next trip.

 

Be sure to run it in recirculation, not fressh air.