[Jeepman]

An operating engine generates heat. Overheating is the more common problem.

Underheating, with a closed system, can only be due to an open thermostat or overly active cooling fans. Since your radiator fans aren't contributing to the problem, it's the thermostat.
A standard replacement 14789 Stant thermostat will work well. It's the most popular replacement on rockauto.com for the 2001.

 

[Ivan Caravan]

Just for reference I took this picture tonight (Jan 10 2021) 6pm after driving about 15 minutes in very light traffic in Metro Vancouver with the outside temp 8c according to my phone. At this point my heater was blowing very warm air although the van wasn’t up to full operating temp yet.

Even in July and August with the AC on full in heavy traffic my gauge never reaches the halfway point.

 

[Jeepman]

Most temperature gauges don't reach the halfway point in my experience, about 1/8" below. Yes, the OP's gauge could be somewhat more faulty, but the heat in the cabin seems to reflect the gauge temperature, i.e. cold, if I understand correctly. If cabin temperature is fine, then the gauge is the only culprit.

 

[Ivan Caravan]

Certainly the Op’s van is running a little cool. That is why I referenced my van’ s gauge and the fact that my heater was blowing very warm air even before my van was up to normal running temp.

 

[bamia]

Should I buy OEM gasket too, it's more expensive than the thermostat, over 45 dollars.

 

[Carbuff2]

My memory is hazy, I put an OEM t-stat in a decade ago, but I thought the gasket (an o-ring) came with the OEM thermostat.

 

[bamia]

I called two dealers in Vancouver, BC, one wanted >45 and the other >60. And neither has the thermostat in stock so I may just order it online.

Any links for OEM thermostat would be appreciated. Is it "Mopar"?

 

[Jeepman]

Should I buy OEM gasket too, it's more expensive than the thermostat, over 45 dollars.

The Mopar name could cost you a bundle for likely a Stant thermostat, if the Dealership even bothers to stock Mopar Thermostats. Here they didn't the last time I tried. Nothing wrong with a Stant thermostat, they are OE in many cases.

Take a look at rockauto.com for expected prices.

2001 DODGE GRAND CARAVAN 3.3L V6 Thermostat | RockAuto

RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. Easy to use parts catalog.

www.rockauto.com

More Information for STANT 14789

The gasket (for the housing/nipple): 2001 DODGE GRAND CARAVAN 3.3L V6 Thermostat / Thermostat Housing / Water Outlet Seal | RockAuto

 

[ScuzziOne]

Somebody double-check me on the part numbers, but I'm not getting numbers quite that high:

Thermostat part # 68210217AA - ~$15

2001-2006 Mopar Water Pump Thermostat 68210217AA | My Mopar Parts

2001-2006 Mopar part # 68210217AA - Water Pump Thermostat

www.mymoparparts.com

Thermostat gasket part # 4781674AA - ~$24

2001-2007 Mopar Water Outlet Gasket 4781674AA | My Mopar Parts

2001-2007 Mopar part # 4781674AA - Water Outlet Gasket

www.mymoparparts.com

Gotta admit the gasket price has gotten a bit crazy though... I only paid $8 for it in 2014!

 

[ScuzziOne]

Complete set, thermostat, thermostat housing, and gasket on ebay for $35 and free shipping (within the US anyway...):

04781387AA Mopar + 68210217AA Mopar Thermostat + Gasket | eBay

04781387AA Mopar + 68210217AA Mopar Thermostat + Gasket. Condition is New. Shipped with USPS Retail Ground.

www.ebay.com

 

[ScuzziOne]

I am, however, assuming this is a 3.3L or 3.8L though. 2.4L parts would be different...

 

[Jeepman]

A Mopar thermostat and housing gasket are no better than Stant (likely are Stant). The total price appears to be less than $16.00 Canadian at rockauto.com. Rockauto has Mopar as well. See links in my previous Post.

 

[bamia]

I am, however, assuming this is a 3.3L or 3.8L though. 2.4L parts would be different...

Yes it is 3.3
Thanks everyone. I will update when I get the parts installed.

 

[Oscarphone]

I think everyone here is in agreement that your thermostat needs to be replaced. Word of caution. Buddy of mine for his 2001 got two, in a row, cheap-o Chineseium thermostats go duff after being installed for just a few weeks. Got the last one from Chrysler and that one cured the problem.