Hi have a xj 01 with no heat inside fan is working pipes out side are hot when running but no heat in side

It may be a problem with your vent control system in your dash. You have a vacuum supply that comes from the top of your engine and travels through your firewall and under your dash to be used to activate the movement of your vent controls. If you have a break in this vacuum line, your vents will not move to change from cool to hot air regardless of where you put your control dial.
That could be your problem.......... or your heater core could be plugged. The core is a mini rad that is under your dash. It takes in hot engine coolant and acts as the heat source. This mini rad sometimes plugs up from ordinary use. Deposits slowly gather up and eventually clog up this rad making it useless. This rad may need to be replaced. Even though your pipes going under your dash are hot, the flow is probably very very slow and not giving enough flow to create heat for you inside your car.
You maybe able to flush out the mini rad by waiting till the engine is cold, then disconnect both hoses under the hood going under the dash, blow out most of the coolant remaining in the heater core(if you can)( also be careful of your eyes) then block one of the lines and put some rad flush through the other line(use a funnel with a hose attached). Leave it there for a while then try running water through it with a garden hose. Be careful to not splash the rad flush fluid in your eyes(wear safety glasses and also wear gloves. Repeat if you feel. Try to flush out as much of the rad flush as you can before reattaching the hoses. Remember to add some coolant cause you will lose some. It would be better to add coolant to the heater core before you attach the hoses to get most of the air out of the system. Good luck