Need to remove my 3 way actuator from my Rinnai 110cn system

On the Durango there may be 3 or 4 actuators referring to the heating and A/C system or 1 if your talking about the door entering or exiting the vehicle. If it's the vehicle door, its behind the door panel of each door and not hard to locate, remove and replace. If it's the heating and A/C actuator you need to determine if it's for center vents, heater control, outside vent air or defrost. Once you determine that you need to go online in YouTube and in the browser select which actuator you want for removal and replacement. That is the best way to approach the problem. If you cannot determine which actuator is the problem, have a professional determine it if you want to tackle the job yourself. In the worst case you may have to pull the dash, remove the under dash suitcase and it could take hours.

F-1-No communication between indoor and outdoor. Comms Error, check your wiring, remove external pumps. Split/Multi - check volts from terminal N to 3 = 0 - 65 Vdc, Multi V - 4 Vdc terminals 3 and 4

Cause: Negative pressure on vent system (pressure difference)
Solution: Check vent system. Vent system and air intake system must be installed according installation instructions. IF vent system is OK: Replace fan

your blend door actuator gear is slipping. remove actuator and check blend door for free movement. If jammed, you may have to open the system to unjam. If door is free to moe, replace actuator. See procedure below to access blend door. Not sure you need a lift, as long as you can get the 2 nuts off under the truck.

Removal & Installation

1. Position the vehicle on a hoist with the gear selector in NEUTRAL.
2. Remove the left-side quarter trim panel.
3. Remove the parts in the order indicated in the following illustration and table.

Fig. Blend door actuator - auxiliary

(1) Auxiliary line floor pan bracket nut (2 req'd)
(2) Auxiliary housing bolt
(3) Auxiliary housing bolt
(4) Auxiliary housing nut
(5) Auxiliary harness electrical connector
(6) Blend door actuator electrical connector
(7) Screw (3 req'd)
(8) Blend door actuator

To install:

1. Installation is the reverse of the removal procedure.
2. Observe the following tightening specifications:
   
   Auxiliary line floor pan bracket nut (2 req'd), 71 inch lbs. (8 Nm) Auxiliary housing bolts, 62 inch lbs (7 Nm) Auxiliary housing nut, 62 inch lbs (7 Nm)
   

Flow meters can get jammed by silt or debrise. The only way that I know to check this problem it to remove & inspect the part and that takes alot of training if you have a Rinnai (not recommended for the beginner).

One thing you could check is the inlet screen. Turn off the water and power to the unit and drain down. The screen in the black plastic circle on the inlet fitting under the unit. Unscrew this and check how much grit it has collected. Clean off, replace, turn water back on, open a hot faucet to get the air out then turn the power back on. This sometimes improves the flow enough to solve the problem.

If it's a new install: the water is going backwards through the heater and you need to check that your cold water IN is actually hooked up to the cold water IN spot on the heater. they don't register flow if the flow goes backwards through the heater.
If it's not a new install: something is stuck in your flow sensor, drain the unit and take it out to check.

I would contact your gas company first and ask if they are trained in Rinnai repair. I would also contact Rinnai (USA) at 800-621-9419 and ask them if they have an service agent in your area.

What type of pipes are install on this heater?

I wonder if you have this problem below caused by a drop in water pressure from someone flushing a toilet or a washing machine. I would call the company to remedy this issue.

17. What is a cold water sandwich effect? The term “cold water sandwich effect” is a term that is used to describe the introduction of cold water into the hot water supply line during frequent on/off operation of an instantaneous water heater. The cold water sandwich effect, when present, appears as a momentary drop in hot water temperature as it is discharged from a hot water supply outlet (i.e. shower, tub, or faucet). This phenomenon is present in the operation of all instantaneous, tankless style, water heaters, but is minimized with the high tech design of Rinnai water heaters.
The technology built into the Rinnai water heaters is designed to minimize the cold water sandwich effect. Rinnai water heaters are microprocessor controlled and when water flow through them ceases, they remain in a “ready to fire state” for approximately 1 minute. If water flow through a Rinnai water heater begins within the first minute following water flow stoppage, the water heater will fire back up within 1 to 2 seconds. This minimizes the cold water sandwich effect that would otherwise be experienced with a low tech tankless water heater. It should be noted that the cold water sandwich effect cannot be removed completely from tankless style water heaters. The safety standards developed to insure the safe operation of water heaters require a delay in the ignition sequence of all gas water heaters.
While the cold water sandwich effect cannot be completely eliminated from standard plumbing systems, it can be eliminated from plumbing systems that have a supply and return hot water circulating system. Rinnai has developed 2 methods to eliminate the cold water sandwich effect in residential hot water circulating systems.
The first (and preferred) method to remove the cold water sandwich from circulating systems utilizes a small electric tank water heater (powered up) that is used with a dual purpose. The small water heater acts as a mixing tank to eliminate the cold water sandwich effect from the Rinnai water heater and it uses its electric heating element to offset the heat losses from the hot water circulating system.
The second method to remove the cold water sandwich from circulating systems utilizes a small 2 to 6 gallon storage tank installed on the hot water outlet of the Rinnai water heater. This tank acts as a mixing tank to blend the cold water sandwich with hot water and eliminating its effect at fixtures.

if it's a gas unit you mite have to bleed the gas line in and out.