Do you know what the system was refilled with? Different coolant types are generally incompatible and can gel when mixed. Best is to go to jagrepair.com, find the vehicle spec guide and double check the exact coolant type your engine calls for. It's going to be between the older green stuff and the newer dexcool orange stuff.

 

Shop receipt shows OEM 50/50 Universal Coolant and OEM BG Coolant System Flush Kit used. No brand names mentioned.

 

Spec: (WSS is orange DEXCOOL). What does your car call for?

 

According to your chart - Dow D542

 

No such animal as "universal coolant". If whatever coolant your car is running now does not meet the required specs, you are in for a world of hurt....

 

I don't trust anything "universal" either. Mine is solidly in the Dexcool camp. The cooling system is complex enough without coolant issues.

 

TSB 303-11

 

UPDATE: After going through all of the suggestions from the forum and other videos, I FINALLY managed to get to the local shop and have them back flush the heater core. There was some yellowish gooey fluid buildup in the hoses and the actual core, but it later cleared. At first the heat amount was not that much better but as I drove it around after picking up, it got warmer and warmer. I think I now have adequate heat in the car. Thanks for everyone's suggestions.