As nearly as I can tell our cab heater system has no in line valve that closes/opens coolant flow to the heater core (e.g. coolant flows all the time) rather whether or not you get cab heat vs. no heat depends on the position of various air flow doors that are, I believe, all vacuum controlled. Hence proper supply of vacuum to that system is critical. I've listened to mine carefully as I change settings and compared to older systems operation of the doors is very quiet but if you listen carefully you can hear air flow direction changes as the controls are manipulated.

nissanfrontier - if you have not already done so visit Sam's NOOB guide and get copies of the 2005 and 2006 factory service manuals. You need both as the 2005 lacks diesel cooling info and the diagnostics, which were in separate books in 2005, and the 2006 illustrations lack keys which the 2005 FSM has. The viscous heater is located at top front passenger side of the engine and if you trace the hoses from the tstat the heater hose runs from the tstat to the viscous heater and then to the heater core in the cab. The viscous heater's function is to provide a bit of boost to the cab heat when the engine is first started and after coolant reaches a certain temp the viscous heater stops doing its thing. In my location I consider it a total waste of space and just something that may break someday so I've pulled the relay to disable it entirely (e.g. serpentine belt spins viscous heater clutch but the clutch never engages so as long as the bearing is ok I'm ok). It may make a difference in colder climates but I've found that plugging the block heater in when the ambient temp gets into the 20sF does just fine to produce cabin heat essentially immediately.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

Ok played with jeep some more switch vicious heater relay with wiper relay still no change. I do hear doors opening and closing in HVAC. Motor seems to stay really cold now after letting dealer do timing belt change. Right around lower 1/4 hash mark not towards center temp normal. I pulled the coolant tank cap and ran jeep in driveway with heat turned on incase there was air in system level stays same. Now I am thinking thermo might be problem, would they have to drop radiator to do timing belt change. I am assuming they did. I drove to store and came back and could take cap of coolant res no pressure. I am getting pissed at these dealerships really all good ones died. I am getting to point I will sell this jeep off see if I can swap for 2011 4dr sport wrangler with the lousy 3.8 for couple grand diff. Still love the jeep and diesel but I am tired of wrenching.

Dude that would be a shame to do to the little diesel it is and easy fix and a part that is know to have a shelf life on any vehical. Just replace it and be happy with the jeep what other SUV can you think of that will tow 5K and still pull 20 mpg. I cant think of a single one The dealer has no need to remove the radiator to do the timing belt change so there is no possible way they could of done damage to the thermostat. Just replace it I mean it is nice and easy and I think you may be blowing this slightly out of proportion. I know that these little things add up and yes it sucks that it happens right after your timing belt change mine happened 1k before mine. But if you keep these little engines happy they will last forever or atleast as long as you plan on keeping it. Just read the Noob guide and treat it as the CRD bible considering we have all contributed and some have had 5+ years of experience. So we know how to keep them happy and running right.

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My CRD Build Thread
Soon to Come:more lights

I hope this is easy fix heck I can not even find HOAT coolant. Is the thermostat easy to access. Is there diagrams that show step by step plus correct bleeding procedure cooling system. I have worked with BMW systems that seem similar, there should be drain on motor block,peecock,bleeder to allow air come out because it's time to get some new coolant and flush it out. This project will be on back burner until I can get jeep running after yesterday fiasco.

- Carefully inspect the hoses. One of my viscose heater hoses was being eaten through by the engine cover.

I second that! One of my viscose hoses was getting a hole worn into it from a poorly positioned upper radiator hose clamp.
Someone had their fingers in there before.
I went to dealer to buy the preformed hose to replace it, and you can't, you must buy them all as an assembly, $94.00 with tax.

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TWO Identical 2005 Liberty Sport CRDS
#1 CRD, 174,000 miles. Eco tune, Samco hoses. Mobil1 0-40w used since day one
#2 CRD 143,000 miles. Bought used (unknown history) with 100,000 miles. Samco hoses.
Eco tune, new rockers, and 5 volt glow plugs installed at 124,000 miles

I am the kind of person who doesn't want to go back in there twice, and not at all until another 100,000 miles, so for me it was cheap insurance to do the water pump and thermostat when doing a T-belt. Besides I don't like to be left walking, if 25 years as a master tech has taught me anything, it is better to do the job right the first time, short cuts, and being frugal never work out for the best.

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JEEP the toughest Four Letter Word In Off-Road

Don't start until you have the correct coolant! Go to the dealer if you have to @$17.00 a gallon.
Others can point to a thread here on this, but short version; Put a hose on radiator petcock and open petcock to drain into a bucket
After coolant bottle is empty remove cap and continue to drain. There are not any drains on the block . You cannot get coolant out of the lower radiator hose unless you remove it, I didn't.
I did not flush either of my CRDs as the coolant looked fine and was just 5 years old.
Not required, but during the thermostat replace, I ended up removing the viscose heater to allow room to scrape the gasket off of the head to avoid gouging the aluminum.
Refill through coolant bottle, the air vents itself out.

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TWO Identical 2005 Liberty Sport CRDS
#1 CRD, 174,000 miles. Eco tune, Samco hoses. Mobil1 0-40w used since day one
#2 CRD 143,000 miles. Bought used (unknown history) with 100,000 miles. Samco hoses.
Eco tune, new rockers, and 5 volt glow plugs installed at 124,000 miles