3.4 running cool, thermostat? - TerrainForum.net: GMC Terrain Forum
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post #1 of 10 (permalink) Old 12-12-2017, 11:04 AM Thread Starter
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3.4 running cool, thermostat?

'05 Equinox with 3.4 has been running cool ever since I bought it about 2 years ago. In the winter it runs between the first tick and the middle tick on the temp gauge, and the heat coming out of the vents is sort of warm but not enough to keep the car feeling warm when it's cold out. It was 18F last night (which isn't that cold for around here) and the car wasn't even getting very comfortable after driving in town for a while. The first winter I owned the car I put in a new thermostat, it was an aftermarket one but I don't remember the brand. It didn't change how the car warmed up. So, as I was replacing the broken lifter a couple weeks ago, I put in another new thermostat, assuming that the one I put in last year was defective, or whatever. This time I paid attention, it was a Murray brand 195 degree thermostat from O'reillys. No improvement, it does the exact same thing. Is there anything that I might be doing wrong in the install? I use that bleed screw afterward and I believe I'm getting all of the air out. Are these engines picky about what t'stat you use? Maybe I should try an oem one? Thanks,
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post #2 of 10 (permalink) Old 12-12-2017, 11:19 AM
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What do the hoses feel like? Are they getting hot? Maybe your temp sensor is lying to you (although Iíd say thatís not likely). Could also have a rusted out water pump with impellers that cannot move the fluid sufficiently.

With regard to your heat, can you feel heat on *those* hoses (at the firewall)? If only on one side, you need a backflush of your heater core? I had this problem (chronically) with my Ď97 Taurus and just made a couple of 6í flush hoses out of garden hose remnants, some brass couplings, hose clamps, and coolant hose pieces. Then you just attach these to your good garden hose, your spigot, on one end, and a suitable point in the engine compartment at the other end (doesnít necessarily have to be *right at* the firewall), and let it rip for 10 seconds on each hose. Catch the output in a big yellow pan and see all the crud that comes out!
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Last edited by Colt Hero; 12-12-2017 at 11:24 AM.
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post #3 of 10 (permalink) Old 12-12-2017, 11:20 AM
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As far as thermostats I would go with either OEM or a Stant. I'm surprised you haven't gotten a CEL for a code for the temp sensor which can mean either that or the thermostat. Does your CEL illuminate on start-up to make sure it's not burnt out? Even if it does, might not hurt to have one of the auto parts chains like Autozone do a free scan for you. I guess you could try the old cardboard in front of the radiator hack to see if you can bring the temp up and get some heat out of the HVAC system during the cold winter months if nothing else, just keep an eye on the temp gauge.
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post #4 of 10 (permalink) Old 12-12-2017, 11:29 AM
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Quote:
Originally Posted by davesupra View Post
'05 Equinox with 3.4 has been running cool ever since I bought it about 2 years ago. In the winter it runs between the first tick and the middle tick on the temp gauge, and the heat coming out of the vents is sort of warm but not enough to keep the car feeling warm when it's cold out. Are these engines picky about what t'stat you use? Maybe I should try an oem one? Thanks,

It may not be the thermostat. It may be a stuck , damaged, or partially defective Blend Door Actuator. Lot's of threads here on how to check and fix that.

The Blend Door, allows a mix of outside (now cold) air with either heated or cooled AC air. If the Door is stuck or damaged, it may be allowing too much cold air to route to the vents.

Try this . . . with the car key in the Acc position, fan on lowest speed, try turning the temperature control knob up. . . . and then down slowly. Listen to see if you can detect a difference in air flow and sound out of the vents. Also listen for any "clicking" sound you may hear coming from the passenger side of the center floor console.

Also, maybe check the hoses going to and from the heater core at the firewall. Both should be warm/hot after the engine is warmed up. If just a little warm, then perhaps clogged heater core. Disconnect and plug the heater core hoses and try a reverse flush with a hose or chemical cleaner.

Note - - not to be confused with the Mode Door. . . . different thing. Affects Defrost and Upper Dash and Lower feet air flow.
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Last edited by JayTee2014; 12-12-2017 at 11:46 AM.
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post #5 of 10 (permalink) Old 12-12-2017, 11:33 AM
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I read the 1st post-- and though-- blend door.

Jaytee posted exactly what I was thinking.


If it was the thermostat--- the CEL would have popped up with a P0128- for not heating up fast enough (open thermostat)
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post #6 of 10 (permalink) Old 12-12-2017, 11:43 AM
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Also . . . .

there is a chance the heater core may be partially clogged up. You could try flushing it..

Here is a link from a previous owner who had just that.

http://www.equinoxforum.net/34-inter...ater-core.html

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Last edited by JayTee2014; 12-12-2017 at 11:47 AM.
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post #7 of 10 (permalink) Old 12-12-2017, 05:23 PM Thread Starter
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Wow, thanks for all of the great ideas guys.

I haven't got any CEL's since I put the top end of the engine back together a couple of weeks ago.

Is the blend door vacuum operated?

I'll start with your easiest suggestions and go from there. Since the temp gauge reads low, I will try the cardboard over the radiator trick first and see if the gauge reads higher and inside air gets warmer.

Thanks again,
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post #8 of 10 (permalink) Old 12-12-2017, 10:09 PM
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Good catch by JayTee2014 about the Blend Door Actuator. Forgot all about that possibility. Surprised, too, because I've had to replace TWO of those on my Taurus.

The following is a description on my Taurus, which *may* be similar to your vehicle:

The Blend Door Actuator (BDA) is just a 3" square X 3/4" thick plastic box (held in by 4 screws under the dash, toward the firewall, in the center). It has a single electrical plug connection and fits into the Blend Door Housing (BDH) to blend hot and cool air. You change the temp setting on the dash and the BDA turns to move the air Blend Door. It has a ~1.5" protruding plastic grooved shaft sticking out at a 90-degree angle (this is the part that plugs into the BDH). Inside is a mess of tiny plastic gears. Failure mode is cracked teeth on tiny interior gear which causes the BDA to lift the blend door only so far ... then it falls down (repeatedly making a clunking or clicking noise). As temporary workaround, was able to prop the Blend Door UP (in the HEAT position) by fashioning a piece of plastic and jamming it into a thin, metal "arm" that moves on the exterior of the BDH. Replaced the Actuator later.

So try moving your temp setting and watching under the dash to see if you can see (and hear) the BDA working. Feel the air coming out the vents. If the engine is hot, and you can feel *some* heat, and there's no "clicking" or "clunking" going on, your BDA is probably OK. I'd try flushing the Heater Core next. Then maybe the Water Pump after that.

Of course, I suppose it's also possible that your BDA has failed (or frozen) in a partial-heat position. Not sure if you'll be able to determine this without pulling it out (still electrically-connected), and watching the shaft turn as you turn the temp knob on the dash. And then even if it turns, is it turning the *full* range?? Might be hard to tell without something to compare it to. Can't remember how my my Taurus shaft turned, but it was probably at least 90 degrees?
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Last edited by Colt Hero; 12-12-2017 at 10:13 PM.
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post #9 of 10 (permalink) Old 10-14-2019, 09:48 AM
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Too bad folks rarely post the out come of their efforts, out of respect for others trying to help them!
Anyway, lately my 2.4L engine runs cooler than I remember in the past, (one tick to the left of the center tick on the gauge.), not alarming, but different from what I remember. It warms up quickly and I get plenty of hot air from the heater system, so it's not that it isn't getting hot, my concern is that it isn't getting hot enough.

If the engine doesn't get hot enough, water condensation in the oil will never boil-off. This will lead to corrosion of the crankshaft bearing journals and any other iron/steel parts, as well as no lubrication on start-up as water will be the first liquid picked up by the oil pump. In my case I'm going to put the scanner on my engine on my way to work, and maybe I just need to replace my thermostat with high high temperature one.

While the oil is still likely getting hot enough, as we head into winter, anybody who notices this should be aware of the points I mentioned above.

Last edited by lou-in-usa; 10-14-2019 at 09:54 AM.
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post #10 of 10 (permalink) Old 10-15-2019, 08:15 AM
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The problem may be with either your temp gauge, or the sender. I would not going with a different thermostat than one with factory specs.

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