What would make a newly installed heater hose malfunction?

What do you mean malfunction, did it blow out, is it leaking at a fitting? Please give more details. Why was the old one replaced?

The story: Went to my mechanic for maintenance and he suggested I change the heater hose on my Infiniti FX 35 due to wear and tear otherwise the car will overheat and stop me on the highway. He replaced the heater hose and a month later the car over heated and stopped me in the middle of I-75 interstate. I took the car to the Infiniti dealership who told me either my mechanic didn't change the heater hose, or he installed it incorrectly which caused the car to overheat and stalled on the highway. Because the car overheated caused a crack in the radiator which will have to be replaced along with the thermostat and other hoses. So is it possible that installing the heater hose improperly can cause the car to over heat and cause a crack in the radiator or the dealership trying to milk me. My car is 2012 Infiniti FX 35 with 170K miles and adequately serviced routinely by the dealership except this time. Thanks

Yep, that is possible, if you had images to upload, I can confirm the problem. It may have been a defective part as well. Did they say it rubbed through or fell off? I am sorry for your troubles.

No images. After the mechanic replaced the heater hose my car started fogging up and the car heater wasn't warming up as fast as it used to. They say those are warning signs of a failing heater hose. Please can you explain to me what would make a new replaced heater hose to fail? Thanks.

When you say fogging up do you mean the windshield? If the mechanic is too rough with the heater hose it can cause the heater core to failure fyi. Also how did the hose fail, blow out or tear, rub through? I need more details.

The heater hose didn't fail. He recommended changing it because of the age of the car. Nothing was wrong with it, just regular maintenance recommendation.

It was the windshield that was fogging up.

Check the passenger's carpet for coolant, if so, the heater core has failed. How did the second heater hose fail?